Diatomaceous energy storage devices

ABSTRACT

The disclosed technology generally relates to energy storage devices, and more particularly to energy storage devices comprising frustules. According to an aspect, a supercapacitor comprises a pair of electrodes and an electrolyte, wherein at least one of the electrodes comprises a plurality of frustules having formed thereon a surface active material. The surface active material can include nanostructures. The surface active material can include one or more of a zinc oxide, a manganese oxide and a carbon nanotube.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/536,112, filed Aug. 8, 2019, entitled “Diatomaceous Energy StorageDevices,” which is a continuation of U.S. patent application Ser. No.15/926,896, filed Mar. 20, 2018, entitled “Diatomaceous Energy StorageDevices,” which is a continuation-in-part of U.S. patent applicationSer. No. 15/808,757, filed Nov. 9, 2017, entitled “Diatomaceous EnergyStorage Devices,” which is a continuation of U.S. patent applicationSer. No. 15/406,407, filed Jan. 13, 2017, entitled “Diatomaceous EnergyStorage Devices,” which is a continuation of U.S. patent applicationSer. No. 14/745,709, filed Jun. 22, 2015, entitled “Diatomaceous EnergyStorage Devices,” which is continuation-in-part of U.S. patentapplication Ser. No. 14/161,658, filed Jan. 22, 2014, entitled“Diatomaceous Energy Storage Devices,” which claims the benefit of U.S.Provisional Patent Application Ser. No. 61/862,469, filed Aug. 5, 2013,entitled “High Surface Area Nanoporous Energy Storage Devices,” andwhich is a continuation-in-part of U.S. patent application Ser. No.13/944,211, filed Jul. 17, 2013, entitled “Diatomaceous Energy StorageDevices,” which claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/750,757, filed Jan. 9, 2013, entitled“Diatomaceous Energy Storage Devices,” and U.S. Provisional PatentApplication Ser. No. 61/673,149, filed Jul. 18, 2012, entitled“Diatomaceous Energy Storage Devices,” each of which is incorporatedherein by reference in its entirety.

BACKGROUND Field

The present application relates to energy storage devices, andparticularly to energy storage devices comprising frustules of diatoms.

Description of the Related Art

Diatoms typically include unicellular eukaryotes, such as single-celledalgae. Diatoms are abundant in nature and can be found in both freshwater and marine environments. Generally, diatoms are enclosed by afrustule having two valves fitted together through a connective zonecomprising girdle elements. Diatomaceous earth, sometimes known asdiatomite, can be a source of frustules. Diatomaceous earth comprisesfossilized frustules and can be used in a diverse range of applications,including as a filtering agent, a filling agent for paints or plastics,an adsorbent, cat litter, or an abrasive material.

Frustules often comprise a significant amount of silica (SiO₂), alongwith alumina, iron oxide, titanium oxide, phosphate, lime, sodium,and/or potassium. Frustules are typically electrically insulating.Frustules may comprise a wide variety of dimensions, surface features,shapes, and other attributes. For example, frustules may comprisediverse shapes, including but not limited to cylinders, spheres, discs,or prisms. Frustules comprise a symmetrical shape or a non-symmetricalshape. Diatoms may be categorized according to the shape and/or symmetryof the frustules, for example grouping the diatoms based on existence orlack of radial symmetry. Frustules may comprise dimensions within arange from less than about one micron to about hundreds of microns.Frustules may also comprise varying porosity, having numerous pores orslits. Pores or slits of frustules may vary in shape, size, and/ordensity. For example, frustules may comprise pores having dimensionsfrom about 5 nm to about 1000 nm.

Frustules may comprise significant mechanical strength or resistance toshear stress, for example due to the dimensions of the frustule,frustule shape, porosity, and/or material composition.

SUMMARY

An energy storage device such as a battery (e.g., rechargeable battery),fuel cell, capacitor, and/or supercapacitor (e.g., electric double-layercapacitor (EDLC), pseudo capacitor, symmetric capacitor), may befabricated using frustules embedded in at least one layer of the energystorage device. The frustules can be sorted to have a selected shape,dimension, porosity, material, surface feature, and/or another suitablefrustule attribute, which may be uniform or substantially uniform orwhich may vary. The frustules may include a frustule surface modifyingstructure and/or material. The energy storage device may include layerssuch as electrodes, separators, and/or current collectors. For example,a separator may be positioned between a first electrode and a secondelectrode, a first current collector may be coupled to the firstelectrode, and a second current collector may be coupled to the secondelectrode. At least one of the separator, the first electrode, and thesecond electrode may include the frustules. Inclusion of frustules in atleast a portion of an energy storage device can help to fabricate theenergy storage device using printing technology, including screenprinting, roll-to-roll printing, ink-jet printing, and/or anothersuitable printing process. The frustules can provide structural supportfor an energy storage device layer and help the energy storage devicelayer to maintain a uniform or substantially uniform thickness duringmanufacturing and/or use. Porous frustules can allow unimpeded orsubstantially unimpeded flow of electrons or ionic species. Frustulesincluding surface structures or material can increase conductivity of alayer.

In some embodiments, a printed energy storage device comprises a firstelectrode, a second electrode, and a separator between the firstelectrode and the second electrode. At least one of the first electrode,the second electrode, and the separator includes frustules.

In some embodiments, the separator includes the frustules. In someembodiments, the first electrode includes the frustules. In someembodiments, the separator and the first electrode include thefrustules. In some embodiments, the second electrode includes thefrustules. In some embodiments, the separator and the second electrodeinclude the frustules. In some embodiments, the first electrode and thesecond electrode include the frustules. In some embodiments, theseparator, the first electrode, and the second electrode include thefrustules.

In some embodiments, the frustules have a substantially uniformproperty. In some embodiments, the property comprises shape, for exampleincluding a cylinder, a sphere, a disc, or a prism. In some embodiments,the property comprises a dimension, for example including diameter,length, or a longest axis. In some embodiments, the property comprisesporosity. In some embodiments, the property comprises mechanicalstrength.

In some embodiments, the frustules comprise a surface modifyingstructure. In some embodiments, the surface modifying structure includesa conductive material. In some embodiments, the conductive materialincludes at least one of silver, aluminum, tantalum, copper, lithium,magnesium, and brass. In some embodiments, the surface modifyingstructure includes zinc oxide (ZnO). In some embodiments, the surfacemodifying structure comprises a semiconductor. In some embodiments, thesemiconductor includes at least one of silicon, germanium, silicongermanium, and gallium arsenide. In some embodiments, the surfacemodifying structure comprises at least one of a nanowire, ananoparticle, and a structure having a rosette shape. In someembodiments, the surface modifying structure is on an exterior surfaceof the frustules. In some embodiments, the surface modifying structureis on an interior surface of the frustules. In some embodiments, thesurface modifying structure is on an interior surface and an exteriorsurface of the frustules.

In some embodiments, the frustules comprise a surface modifyingmaterial. In some embodiments, the surface modifying material comprisesa conductive material. In some embodiments, the surface modifyingmaterial includes at least one of silver, aluminum, tantalum, copper,lithium, magnesium, and brass. In some embodiments, the surfacemodifying material includes ZnO. In some embodiments, the surfacemodifying material includes a semiconductor. In some embodiments, thesemiconductor includes at least one of silicon, germanium, silicongermanium, and gallium arsenide. In some embodiments, the surfacemodifying material is on an exterior surface of the frustules. In someembodiments, the surface modifying material is on an interior surface ofthe frustules. In some embodiments, the surface modifying material is onan exterior surface and an interior surface of the frustules.

In some embodiments, the first electrode comprises a conductive filler.In some embodiments, the second electrode comprises a conductive filler.In some embodiments, the first electrode and the second electrodecomprise a conductive filler. In some embodiments, the conductive fillercomprises graphitic carbon. In some embodiments, the conductive fillercomprises graphene. In some embodiments, the conductive filler comprisescarbon nanotubes.

In some embodiments, the first electrode comprises an adherencematerial. In some embodiments, the second electrode comprises anadherence material. In some embodiments, the first electrode and thesecond electrode comprise an adherence material. In some embodiments,the separator comprises an adherence material. In some embodiments, thefirst electrode and the separator comprise an adherence material. Insome embodiments, the second electrode and the separator comprise anadherence material. In some embodiments, the first electrode, the secondelectrode, and the separator comprise an adherence material. In someembodiments, the adherence material comprises a polymer.

In some embodiments, the separator comprises an electrolyte. In someembodiments, the electrolyte comprises at least one of an ionic liquid,an acid, a base, and a salt. In some embodiments, the electrolytecomprises an electrolytic gel.

In some embodiments, the device comprises a first current collector inelectrical communication with the first electrode. In some embodiments,the device comprises a second current collector in electricalcommunication with the second electrode. In some embodiments, the devicecomprises a first current collector in electrical communication with thefirst electrode and a second current collector in electricalcommunication with the second electrode.

In some embodiments, the printed energy storage device comprises acapacitor. In some embodiments, the printed energy storage devicecomprises a supercapacitor. In some embodiments, the printed energystorage device comprises a battery.

In some embodiments, a system comprises a plurality of the printedenergy storage devices as described herein stacked on top of each other.In some embodiments, an electrical device comprises the printed energystorage devices described herein or the system.

In some embodiments, a membrane for a printed energy storage devicecomprises frustules.

In some embodiments, the frustules have a substantially uniformproperty. In some embodiments, the property comprises shape, for exampleincluding a cylinder, a sphere, a disc, or a prism. In some embodiments,the property comprises a dimension, for example including diameter,length, or a longest axis. In some embodiments, the property comprisesporosity. In some embodiments, the property comprises mechanicalstrength.

In some embodiments, the frustules comprise a surface modifyingstructure. In some embodiments, the surface modifying structure includesa conductive material. In some embodiments, the conductive materialincludes at least one of silver, aluminum, tantalum, copper, lithium,magnesium, and brass. In some embodiments, the surface modifyingstructure includes zinc oxide (ZnO). In some embodiments, the surfacemodifying structure comprises a semiconductor. In some embodiments, thesemiconductor includes at least one of silicon, germanium, silicongermanium, and gallium arsenide. In some embodiments, the surfacemodifying structure comprises at least one of a nanowire, ananoparticle, and a structure having a rosette shape. In someembodiments, the surface modifying structure is on an exterior surfaceof the frustules. In some embodiments, the surface modifying structureis on an interior surface of the frustules. In some embodiments, thesurface modifying structure is on an interior surface and an exteriorsurface of the frustules.

In some embodiments, the frustules comprise a surface modifyingmaterial. In some embodiments, the surface modifying material comprisesa conductive material. In some embodiments, the surface modifyingmaterial includes at least one of silver, aluminum, tantalum, copper,lithium, magnesium, and brass. In some embodiments, the surfacemodifying material includes ZnO. In some embodiments, the surfacemodifying material includes a semiconductor. In some embodiments, thesemiconductor includes at least one of silicon, germanium, silicongermanium, and gallium arsenide. In some embodiments, the surfacemodifying material is on an exterior surface of the frustules. In someembodiments, the surface modifying material is on an interior surface ofthe frustules. In some embodiments, the surface modifying material is onan exterior surface and an interior surface of the frustules.

In some embodiments, the membrane further comprises a conductive filler.In some embodiments, the conductive filler comprises graphitic carbon.In some embodiments, the conductive filler comprises graphene.

In some embodiments, the membrane further comprises an adherencematerial. In some embodiments, the adherence material comprises apolymer.

In some embodiments, the membrane further comprises an electrolyte. Insome embodiments, the electrolyte comprises at least one of an ionicliquid, an acid, a base, and a salt. In some embodiments, theelectrolyte comprises an electrolytic gel.

In some embodiments, an energy storage device comprises the membrane asdescribed herein. In some embodiments, the printed energy storage devicecomprises a capacitor. In some embodiments, the printed energy storagedevice comprises a supercapacitor. In some embodiments, the printedenergy storage device comprises a battery. In some embodiments, a systemcomprises a plurality of energy storage devices as described hereinstacked on top of each other. In some embodiments, an electrical devicecomprises the printed energy storage devices described herein or thesystem.

In some embodiments, a method of manufacturing a printed energy storagedevice comprises forming a first electrode, forming a second electrode,and forming a separator between the first electrode and the secondelectrode. At least one of the first electrode, the second electrode,and the separator includes frustules.

In some embodiments, the separator includes the frustules. In someembodiments, forming the separator includes forming a dispersion of thefrustules. In some embodiments, forming the separator includes screenprinting the separator. In some embodiments, forming the separatorincludes forming a membrane of the frustules. In some embodiments,forming the separator includes roll-to-roll printing the membraneincluding the separator.

In some embodiments, the first electrode includes the frustules. In someembodiments, forming the first electrode includes forming a dispersionof the frustules. In some embodiments, forming the first electrodeincludes screen printing the first electrode. In some embodiments,forming the first electrode includes forming a membrane of thefrustules. In some embodiments, forming the first electrode includesroll-to-roll printing the membrane including the first electrode.

In some embodiments, the second electrode includes the frustules. Insome embodiments, forming the second electrode includes forming adispersion of the frustules. In some embodiments, forming the secondelectrode includes screen printing the second electrode. In someembodiments, forming the second electrode includes forming a membrane ofthe frustules. In some embodiments, forming the second electrodeincludes roll-to-roll printing the membrane including the secondelectrode.

In some embodiments, the method further comprises sorting the frustulesaccording to a property. In some embodiments, the property comprises atleast one of shape, dimension, material, and porosity.

In some embodiments, an ink comprises a solution and frustules dispersedin the solution.

In some embodiments, the frustules have a substantially uniformproperty. In some embodiments, the property comprises shape, for exampleincluding a cylinder, a sphere, a disc, or a prism. In some embodiments,the property comprises a dimension, for example including diameter,length, or a longest axis. In some embodiments, the property comprisesporosity. In some embodiments, the property comprises mechanicalstrength.

In some embodiments, the frustules comprise a surface modifyingstructure. In some embodiments, the surface modifying structure includesa conductive material. In some embodiments, the conductive materialincludes at least one of silver, aluminum, tantalum, copper, lithium,magnesium, and brass. In some embodiments, the surface modifyingstructure includes zinc oxide (ZnO). In some embodiments, the surfacemodifying structure comprises a semiconductor. In some embodiments, thesemiconductor includes at least one of silicon, germanium, silicongermanium, and gallium arsenide. In some embodiments, the surfacemodifying structure comprises at least one of a nanowire, ananoparticle, and a structure having a rosette shape. In someembodiments, the surface modifying structure is on an exterior surfaceof the frustules. In some embodiments, the surface modifying structureis on an interior surface of the frustules. In some embodiments, thesurface modifying structure is on an interior surface and an exteriorsurface of the frustules.

In some embodiments, the frustules comprise a surface modifyingmaterial. In some embodiments, the surface modifying material comprisesa conductive material. In some embodiments, the surface modifyingmaterial includes at least one of silver, aluminum, tantalum, copper,lithium, magnesium, and brass. In some embodiments, the surfacemodifying material includes ZnO. In some embodiments, the surfacemodifying material includes a semiconductor. In some embodiments, thesemiconductor includes at least one of silicon, germanium, silicongermanium, and gallium arsenide. In some embodiments, the surfacemodifying material is on an exterior surface of the frustules. In someembodiments, the surface modifying material is on an interior surface ofthe frustules. In some embodiments, the surface modifying material is onan exterior surface and an interior surface of the frustules.

In some embodiments, the ink further comprises a conductive filler. Insome embodiments, the conductive filler comprises graphitic carbon. Insome embodiments, the conductive filler comprises graphene.

In some embodiments, the ink further comprises an adherence material. Insome embodiments, the adherence material comprises a polymer.

In some embodiments, the ink further comprises an electrolyte. In someembodiments, the electrolyte comprises at least one of an ionic liquid,an acid, a base, and a salt. In some embodiments, the electrolytecomprises an electrolytic gel.

In some embodiments, a device comprises at least one of the inksdescribed herein. In some embodiments, the device comprises a printedenergy storage device. In some embodiments, the printed energy storagedevice comprises a capacitor. In some embodiments, the printed energystorage device comprises a supercapacitor. In some embodiments, theprinted energy storage device comprises a battery.

A method of extracting a diatom frustule portion may comprise dispersinga plurality of diatom frustule portions in a dispersing solvent. Atleast one of an organic contaminant and an inorganic contaminant may beremoved. The method of extracting a diatom frustule portion may comprisedispersing the plurality of diatom frustule portions in a surfactant,the surfactant reducing an agglomeration of the plurality of diatomfrustule portions. The method may comprise extracting a plurality ofdiatom frustule portions having at least one common characteristic usinga disc stack centrifuge.

In some embodiments, the at least one common characteristic can includeat least one of a dimension, a shape, a material, and a degree ofbrokenness. The dimension may include at least one of a length and adiameter.

In some embodiments, a solid mixture can comprise the plurality ofdiatom frustule portions. The method of extracting a diatom frustuleportion may comprise reducing a particle dimension of the solid mixture.Reducing the particle dimension of the solid mixture may be beforedispersing the plurality of diatom frustule portions in the dispersingsolvent. In some embodiments, reducing the particle dimension cancomprise grinding the solid mixture. Grinding the solid mixture mayinclude applying to the solid mixture at least one of a mortar and apestle, a jar mill, and a rock crusher.

In some embodiments, a component of the solid mixture having a longestcomponent dimension that is greater than a longest frustule portiondimension of the plurality of diatom frustule portions can be extracted.Extracting the component of the solid mixture may comprise sieving thesolid mixture. Sieving the solid mixture may comprise processing thesolid mixture with a sieve having a mesh size from about 15 microns toabout 25 microns. Sieving the solid mixture may comprise processing thesolid mixture with a sieve having a mesh size from about 10 microns toabout 25 microns.

In some embodiments, the method of extracting a diatom frustule portioncan comprise sorting the plurality of diatom frustule portions toseparate a first diatom frustule portion from a second diatom frustuleportion, the first diatom frustule portion having a greater longestdimension. For example, the first diatom frustule portion may comprise aplurality of unbroken diatom frustule portions. The second diatomfrustule portion may comprise a plurality of broken diatom frustuleportions.

In some embodiments, sorting the plurality of diatom frustule portionscan comprise filtering the plurality of diatom frustule portions.Filtering may comprise disturbing agglomeration of the plurality ofdiatom frustule portions. In some embodiments, disturbing agglomerationof the plurality of diatom frustule portions can comprise stirring. Insome embodiments, disturbing agglomeration of the plurality of diatomfrustule portions can comprise shaking. In some embodiments, disturbingagglomeration of the plurality of diatom frustule portions can comprisebubbling.

Filtering may include applying a sieve to the plurality of diatomfrustule portions. For example, the sieve may have a mesh size fromabout 5 microns to about 10 microns, including about 7 microns.

In some embodiments, the method of extracting a diatom frustule portioncan include obtaining a washed diatom frustule portion. Obtaining thewashed diatom frustule portion may comprise washing the plurality ofdiatom frustule portions with a cleaning solvent after removing the atleast one of the organic contaminant and the inorganic contaminant. Insome embodiments, obtaining the washed diatom frustule portion cancomprise washing the diatom frustule portion having the at least onecommon characteristic with a cleaning solvent.

The cleaning solvent may be removed. For example, removing the cleaningsolvent may comprise sedimenting the plurality of diatom frustuleportions after removing at least one of the organic contaminant and theinorganic contaminant. For example, removing the cleaning solvent maycomprise sedimenting the plurality of diatom frustule portions havingthe at least one common characteristic. Sedimenting the plurality ofdiatom frustule portions may comprise centrifuging. In some embodiments,centrifuging can comprise applying a centrifuge suitable for large scaleprocessing. In some embodiments, centrifuging can comprise applying atleast one of a disc stack centrifuge, a decanter centrifuge, and atubular bowl centrifuge.

In some embodiments, at least one of the dispersing solvent and thecleaning solvent can comprise water.

In some embodiments, at least one of dispersing the plurality of diatomfrustule portions in the dispersing solvent and dispersing the pluralityof diatom frustule portions in the surfactant can comprise sonicatingthe plurality of diatom frustules.

The surfactant may comprise a cationic surfactant. For example, thecationic surfactant may comprise at least one of a benzalkoniumchloride, a cetrimonium bromide, a lauryl methyl gluceth-10hydroxypropyl dimonium chloride, a benzethonium chloride, a benzethoniumchloride, a bronidox, a dmethyldioctadecylammonium chloride, and atetramethylammonium hydroxide.

The surfactant may comprise a non-ionic surfactant. For example, thenon-ionic surfactant may comprise at least one of a cetyl alcohol, astearyl alcohol, a cetostearyl alcohol, an oleyl alcohol, apolyoxyethylene glycol alkyl ether, an octaethylene glycol monododecylether, a glucoside alkyl ethers, a decyl glucoside, a polyoxyethyleneglycol octylphenol ethers, an octylphenol ethoxylate (Triton X-100™), anonoxynol-9, a glyceryl laurate, a polysorbate, and a poloxamer.

In some embodiments, the method of extracting a diatom frustule portioncan comprise dispersing the plurality of diatom frustules in an additivecomponent. Dispersing the plurality of diatom frustules in an additivecomponent may be before dispersing the plurality of diatom frustules inthe surfactant. Dispersing the plurality of diatom frustules in anadditive component may be after dispersing the plurality of diatomfrustules in the surfactant. Dispersing the plurality of diatomfrustules in an additive component may be at least partiallysimultaneous with dispersing the plurality of diatom frustules in thesurfactant. The additive component may include at least one of apotassium chloride, an ammonium chloride, an ammonium hydroxide, and asodium hydroxide.

In some embodiments, dispersing the plurality of diatom frustuleportions can comprise obtaining a dispersion comprising about 1 weightpercent to about 5 weight percent of the plurality of diatom frustuleportions.

In some embodiments, removing the organic contaminant can compriseheating the plurality of diatom frustule portions in the presence of ableach. The bleach may include at least one of a hydrogen peroxide and anitric acid. Heating the plurality of diatom frustule portions maycomprise heating the plurality of diatom frustule portions in a solutioncomprising an amount of hydrogen peroxide in a range from about 10volume percent to about 20 volume percent. Heating the plurality ofdiatom frustule portions may comprise heating the plurality of diatomfrustule portions for a duration of about 5 minutes to about 15 minutes.

In some embodiments, removing the organic contaminant can compriseannealing the plurality of diatom frustule portions. In someembodiments, removing the inorganic contaminant can comprise combiningthe plurality of diatom frustule portions with at least one of ahydrochloric acid and a sulfuric acid. Combining the plurality of diatomfrustule portions with at least one of a hydrochloric acid and asulfuric acid may include mixing the plurality of diatom frustuleportions in a solution comprising about 15 volume percent to about 25volume percent of hydrochloric acid. For example, the mixing may be fora duration of about 20 minutes to about 40 minutes.

A method of extracting a diatom frustule portion may include extractinga plurality of diatom frustule portions having at least one commoncharacteristic using a disc stack centrifuge.

In some embodiments, the method of extracting a diatom frustule portioncan comprise dispersing the plurality of diatom frustule portions in adispersing solvent. In some embodiments, the method can compriseremoving at least one of an organic contaminant and an inorganiccontaminant. In some embodiments, the method can comprise dispersing theplurality of diatom frustule portions in a surfactant, the surfactantreducing an agglomeration of the plurality of diatom frustule portions.

The at least one common characteristic may include at least one of adimension, a shape, a material, and a degree of brokenness. Thedimension may include at least one of a length and a diameter.

In some embodiments, a solid mixture can comprise the plurality ofdiatom frustule portions. The method of extracting a diatom frustuleportion may comprise reducing a particle dimension of the solid mixture.Reducing the particle dimension of the solid mixture may be beforedispersing the plurality of diatom frustule portions in the dispersingsolvent. In some embodiments, reducing the particle dimension cancomprise grinding the solid mixture. Grinding the solid mixture mayinclude applying to the solid mixture at least one of a mortar and apestle, a jar mill, and a rock crusher.

In some embodiments, a component of the solid mixture having a longestcomponent dimension that is greater than a longest frustule portiondimension of the plurality of diatom frustule portions can be extracted.Extracting the component of the solid mixture may comprise sieving thesolid mixture. Sieving the solid mixture may comprise processing thesolid mixture with a sieve having a mesh size from about 15 microns toabout 25 microns. Sieving the solid mixture may comprise processing thesolid mixture with a sieve having a mesh size from about 10 microns toabout 25 microns.

In some embodiments, the method of extracting a diatom frustule portioncan comprise sorting the plurality of diatom frustule portions toseparate a first diatom frustule portion from a second diatom frustuleportion, the first diatom frustule portion having a greater longestdimension. For example, the first diatom frustule portion may comprise aplurality of unbroken diatom frustule portions. The second diatomfrustule portion may comprise a plurality of broken diatom frustuleportions.

In some embodiments, sorting the plurality of diatom frustule portionscan comprise filtering the plurality of diatom frustule portions.Filtering may comprise disturbing agglomeration of the plurality ofdiatom frustule portions. In some embodiments, disturbing agglomerationof the plurality of diatom frustule portions can comprise stirring. Insome embodiments, disturbing agglomeration of the plurality of diatomfrustule portions can comprise shaking. In some embodiments, disturbingagglomeration of the plurality of diatom frustule portions can comprisebubbling.

Filtering may include applying a sieve to the plurality of diatomfrustule portions. For example, the sieve may have a mesh size fromabout 5 microns to about 10 microns, including about 7 microns.

In some embodiments, the method of extracting a diatom frustule portioncan include obtaining a washed diatom frustule portion. Obtaining thewashed diatom frustule portion may comprise washing the plurality ofdiatom frustule portions with a cleaning solvent after removing the atleast one of the organic contaminant and the inorganic contaminant. Insome embodiments, obtaining the washed diatom frustule portion cancomprise washing the diatom frustule portion having the at least onecommon characteristic with a cleaning solvent.

The cleaning solvent may be removed. For example, removing the cleaningsolvent may comprise sedimenting the plurality of diatom frustuleportions after removing at least one of the organic contaminant and theinorganic contaminant. For example, removing the cleaning solvent maycomprise sedimenting the plurality of diatom frustule portions havingthe at least one common characteristic. Sedimenting the plurality ofdiatom frustule portions may comprise centrifuging. In some embodiments,centrifuging can comprise applying a centrifuge suitable for large scaleprocessing. In some embodiments, centrifuging can comprise applying atleast one of a disc stack centrifuge, a decanter centrifuge, and atubular bowl centrifuge.

In some embodiments, at least one of the dispersing solvent and thecleaning solvent can comprise water.

In some embodiments, at least one of dispersing the plurality of diatomfrustule portions in the dispersing solvent and dispersing the pluralityof diatom frustule portions in the surfactant can comprise sonicatingthe plurality of diatom frustules.

The surfactant may comprise a cationic surfactant. For example, thecationic surfactant may comprise at least one of a benzalkoniumchloride, a cetrimonium bromide, a lauryl methyl gluceth-10hydroxypropyl dimonium chloride, a benzethonium chloride, a benzethoniumchloride, a bronidox, a dimethyldioctadecylammonium chloride, and atetramethylammonium hydroxide.

The surfactant may comprise a non-ionic surfactant. For example, thenon-ionic surfactant may comprise at least one of a cetyl alcohol, astearyl alcohol, a cetostearyl alcohol, an oleyl alcohol, apolyoxyethylene glycol alkyl ether, an octaethylene glycol monododecylether, a glucoside alkyl ethers, a decyl glucoside, a polyoxyethyleneglycol octylphenol ethers, an octylphenol ethoxylate (Triton X-100™), anonoxynol-9, a glyceryl laurate, a polysorbate, and a poloxamer.

In some embodiments, the method of extracting a diatom frustule portioncan comprise dispersing the plurality of diatom frustules in an additivecomponent. Dispersing the plurality of diatom frustules in an additivecomponent may be before dispersing the plurality of diatom frustules inthe surfactant. Dispersing the plurality of diatom frustules in anadditive component may be after dispersing the plurality of diatomfrustules in the surfactant. Dispersing the plurality of diatomfrustules in an additive component may be at least partiallysimultaneous with dispersing the plurality of diatom frustules in thesurfactant. The additive component may include at least one of apotassium chloride, an ammonium chloride, an ammonium hydroxide, and asodium hydroxide.

In some embodiments, dispersing the plurality of diatom frustuleportions can comprise obtaining a dispersion comprising about 1 weightpercent to about 5 weight percent of the plurality of diatom frustuleportions.

In some embodiments, removing the organic contaminant can compriseheating the plurality of diatom frustule portions in the presence of ableach. The bleach may include at least one of a hydrogen peroxide and anitric acid. Heating the plurality of diatom frustule portions maycomprise heating the plurality of diatom frustule portions in a solutioncomprising an amount of hydrogen peroxide in a range from about 10volume percent to about 20 volume percent. Heating the plurality ofdiatom frustule portions may comprise heating the plurality of diatomfrustule portions for a duration of about 5 minutes to about 15 minutes.

In some embodiments, removing the organic contaminant can compriseannealing the plurality of diatom frustule portions. In someembodiments, removing the inorganic contaminant can comprise combiningthe plurality of diatom frustule portions with at least one of ahydrochloric acid and a sulfuric acid. Combining the plurality of diatomfrustule portions with at least one of a hydrochloric acid and asulfuric acid may include mixing the plurality of diatom frustuleportions in a solution comprising about 15 volume percent to about 25volume percent of hydrochloric acid. For example, the mixing may be fora duration of about 20 minutes to about 40 minutes.

A method of extracting a diatom frustule portion may include dispersinga plurality of diatom frustule portions with a surfactant, thesurfactant reducing an agglomeration of the plurality of diatom frustuleportions.

The method of extracting a diatom frustule portion may includeextracting a plurality of diatom frustule portions having at least onecommon characteristic using a disc stack centrifuge. In someembodiments, the method of extracting a diatom frustule portion cancomprise dispersing a plurality of diatom frustule portions in adispersing solvent. In some embodiments, at least one of an organiccontaminant and an inorganic contaminant may be removed.

In some embodiments, the at least one common characteristic can includeat least one of a dimension, a shape, a material, and a degree ofbrokenness. The dimension may include at least one of a length and adiameter.

In some embodiments, a solid mixture can comprise the plurality ofdiatom frustule portions. The method of extracting a diatom frustuleportion may comprise reducing a particle dimension of the solid mixture.Reducing the particle dimension of the solid mixture may be beforedispersing the plurality of diatom frustule portions in the dispersingsolvent. In some embodiments, reducing the particle dimension cancomprise grinding the solid mixture. Grinding the solid mixture mayinclude applying to the solid mixture at least one of a mortar and apestle, a jar mill, and a rock crusher.

In some embodiments, a component of the solid mixture having a longestcomponent dimension that is greater than a longest frustule portiondimension of the plurality of diatom frustule portions can be extracted.Extracting the component of the solid mixture may comprise sieving thesolid mixture. Sieving the solid mixture may comprise processing thesolid mixture with a sieve having a mesh size from about 15 microns toabout 25 microns. Sieving the solid mixture may comprise processing thesolid mixture with a sieve having a mesh size from about 10 microns toabout 25 microns.

In some embodiments, the method of extracting a diatom frustule portioncan comprise sorting the plurality of diatom frustule portions toseparate a first diatom frustule portion from a second diatom frustuleportion, the first diatom frustule portion having a greater longestdimension. For example, the first diatom frustule portion may comprise aplurality of unbroken diatom frustule portions. The second diatomfrustule portion may comprise a plurality of broken diatom frustuleportions.

In some embodiments, sorting the plurality of diatom frustule portionscan comprise filtering the plurality of diatom frustule portions.Filtering may comprise disturbing agglomeration of the plurality ofdiatom frustule portions. In some embodiments, disturbing agglomerationof the plurality of diatom frustule portions can comprise stirring. Insome embodiments, disturbing agglomeration of the plurality of diatomfrustule portions can comprise shaking. In some embodiments, disturbingagglomeration of the plurality of diatom frustule portions can comprisebubbling.

Filtering may include applying a sieve to the plurality of diatomfrustule portions. For example, the sieve may have a mesh size fromabout 5 microns to about 10 microns, including about 7 microns.

In some embodiments, the method of extracting a diatom frustule portioncan include obtaining a washed diatom frustule portion. Obtaining thewashed diatom frustule portion may comprise washing the plurality ofdiatom frustule portions with a cleaning solvent after removing the atleast one of the organic contaminant and the inorganic contaminant. Insome embodiments, obtaining the washed diatom frustule portion cancomprise washing the diatom frustule portion having the at least onecommon characteristic with a cleaning solvent.

The cleaning solvent may be removed. For example, removing the cleaningsolvent may comprise sedimenting the plurality of diatom frustuleportions after removing at least one of the organic contaminant and theinorganic contaminant. For example, removing the cleaning solvent maycomprise sedimenting the plurality of diatom frustule portions havingthe at least one common characteristic. Sedimenting the plurality ofdiatom frustule portions may comprise centrifuging. In some embodiments,centrifuging can comprise applying a centrifuge suitable for large scaleprocessing. In some embodiments, centrifuging can comprise applying atleast one of a disc stack centrifuge, a decanter centrifuge, and atubular bowl centrifuge.

In some embodiments, at least one of the dispersing solvent and thecleaning solvent can comprise water.

In some embodiments, at least one of dispersing the plurality of diatomfrustule portions in the dispersing solvent and dispersing the pluralityof diatom frustule portions in the surfactant can comprise sonicatingthe plurality of diatom frustules.

The surfactant may comprise a cationic surfactant. For example, thecationic surfactant may comprise at least one of a benzalkoniumchloride, a cetrimonium bromide, a lauryl methyl gluceth-10hydroxypropyl dimonium chloride, a benzethonium chloride, a benzethoniumchloride, a bronidox, a dimethyldioctadecylammonium chloride, and atetramethylammonium hydroxide.

The surfactant may comprise a non-ionic surfactant. For example, thenon-ionic surfactant may comprise at least one of a cetyl alcohol, astearyl alcohol, a cetostearyl alcohol, an oleyl alcohol, apolyoxyethylene glycol alkyl ether, an octaethylene glycol monododecylether, a glucoside alkyl ethers, a decyl glucoside, a polyoxyethyleneglycol octylphenol ethers, an octylphenol ethoxylate (Triton X-100™), anonoxynol-9, a glyceryl laurate, a polysorbate, and a poloxamer.

In some embodiments, the method of extracting a diatom frustule portioncan comprise dispersing the plurality of diatom frustules in an additivecomponent. Dispersing the plurality of diatom frustules in an additivecomponent may be before dispersing the plurality of diatom frustules inthe surfactant. Dispersing the plurality of diatom frustules in anadditive component may be after dispersing the plurality of diatomfrustules in the surfactant. Dispersing the plurality of diatomfrustules in an additive component may be at least partiallysimultaneous with dispersing the plurality of diatom frustules in thesurfactant. The additive component may include at least one of apotassium chloride, an ammonium chloride, an ammonium hydroxide, and asodium hydroxide.

In some embodiments, dispersing the plurality of diatom frustuleportions can comprise obtaining a dispersion comprising about 1 weightpercent to about 5 weight percent of the plurality of diatom frustuleportions.

In some embodiments, removing the organic contaminant can compriseheating the plurality of diatom frustule portions in the presence of ableach. The bleach may include at least one of a hydrogen peroxide and anitric acid. Heating the plurality of diatom frustule portions maycomprise heating the plurality of diatom frustule portions in a solutioncomprising an amount of hydrogen peroxide in a range from about 10volume percent to about 20 volume percent. Heating the plurality ofdiatom frustule portions may comprise heating the plurality of diatomfrustule portions for a duration of about 5 minutes to about 15 minutes.

In some embodiments, removing the organic contaminant can compriseannealing the plurality of diatom frustule portions. In someembodiments, removing the inorganic contaminant can comprise combiningthe plurality of diatom frustule portions with at least one of ahydrochloric acid and a sulfuric acid. Combining the plurality of diatomfrustule portions with at least one of a hydrochloric acid and asulfuric acid may include mixing the plurality of diatom frustuleportions in a solution comprising about 15 volume percent to about 25volume percent of hydrochloric acid. For example, the mixing may be fora duration of about 20 minutes to about 40 minutes.

A method of forming silver nanostructures on a diatom frustule portionmay include forming a silver seed layer on a surface of the diatomfrustule portion. The method may include forming a nanostructure on theseed layer.

In some embodiments, the nanostructures can comprise at least one of acoating, a nanowire, a nanoplate, a dense array of nanoparticles, ananobelt, and a nanodisk. In some embodiments, the nanostructures cancomprise silver.

Forming the silver seed layer may comprise applying a cyclic heatingregimen to a first silver contributing component and the diatom frustuleportion. In some embodiments, applying the cyclic heating regimen cancomprise applying a cyclic microwave power. Applying the cyclicmicrowave power may comprise alternating a microwave power between about100 Watt and 500 Watt. For example, alternating may comprise alternatingthe microwave power every minute. In some embodiments, alternating cancomprise alternating the microwave power for a duration of about 30minutes. In some embodiments, alternating can comprise alternating themicrowave power for a duration of about 20 minutes to about 40 minutes.

In some embodiments, forming the silver seed layer can comprisecombining the diatom frustule portion with a seed layer solution. Theseed layer solution may include the first silver contributing componentand a seed layer reducing agent. For example, the seed layer reducingagent may be a seed layer solvent. In some embodiments, the seed layerreducing agent and the seed layer solvent can comprise a polyethyleneglycol.

In some embodiments, the seed layer solution can comprise the firstsilver contributing component, a seed layer reducing agent and a seedlayer solvent.

Forming the silver seed layer may comprise mixing the diatom frustuleportion with the seed layer solution. In some embodiments, the mixingcan comprise ultrasonicating.

In some embodiments, the seed layer reducing agent can comprise aN,N-Dimethylformamide, the first silver contributing component cancomprise a silver nitrate, and the seed layer solvent can comprise atleast one of a water and a polyvinylpyrrolidone.

Forming the nanostructure may comprise combining the diatom frustuleportion with a nanostructure forming reducing agent. In someembodiments, forming the nanostructure further may include heating thediatom frustule portion after combining the diatom frustule portion withthe nanostructure forming reducing agent. For example, the heating maycomprise heating to a temperature of about 120° C. to about 160° C.

In some embodiments, forming the nanostructure can include titrating thediatom frustule portion with a titration solution comprising ananostructure forming solvent and a second silver contributingcomponent. In some embodiments, forming the nanostructure can comprisemixing after titrating the diatom frustule portion with the titrationsolution.

In some embodiments, at least one of the seed layer reducing agent andthe nanostructure forming reducing agent can comprise at least one of ahydrazine, a formaldehyde, a glucose, sodium tartrate, an oxalic acid, aformic acid, an ascorbic acid, and an ethylene glycol.

In some embodiments, at least one of the first silver contributingcomponent and the second silver contributing component can comprise atleast one of a silver salt and a silver oxide. For example, the silversalt may include at least one of a silver nitrate and an ammoniacalsilver nitrate, a silver chloride (AgC1), a silver cyanide (AgCN), asilver tetrafluoroborate, a silver hexafluorophosphate, and a silverethylsulphate.

Forming the nanostructure may be in an ambient to reduce oxideformation. For example, the ambient may comprise an argon atmosphere.

In some embodiments, at least one of the seed layer solvent and thenanostructure forming solvent can comprise at least one of a propyleneglycol, a water, a methanol, an ethanol, a 1-propanol, a 2-propanol a1-methoxy-2-propanol, a 1-butanol, a 2-butanol a 1-pentanol, a2-pentanol, a 3-pentanol, a 1-hexanol, a 2-hexanol, a 3-hexanol, anoctanol, a 1-octanol, a 2-octanol, a 3-octanol, a tetrahydrofurfurylalcohol (THFA), a cyclohexanol, a cyclopentanol, a terpineol, a butyllactone; a methyl ethyl ether, a diethyl ether, an ethyl propyl ether, apolyethers, a diketones, a cyclohexanone, a cyclopentanone, acycloheptanone, a cyclooctanone, an acetone, a benzophenone, anacetylacetone, an acetophenone, a cyclopropanone, an isophorone, amethyl ethyl ketone, an ethyl acetate, a dimethyl adipate, a propyleneglycol monomethyl ether acetate, a dimethyl glutarate, a dimethylsuccinate, a glycerin acetate, a carboxylates, a propylene carbonate, aglycerin, a diol, a triol, a tetraol, a pentanol, an ethylene glycol, adiethylene glycol, a polyethylene glycol, a propylene glycol, adipropylene glycol, a glycol ether, a glycol ether acetate, a1,4-butanediol, a 1,2-butanediol, a 2,3-butanediol, a 1,3-propanediol, a1,4-butanediol, a 1,5-pentanediol, a 1,8-octanediol, a 1,2-propanediol,a 1,3-butanediol, a 1,2-pentanediol, an etohexadiol, ap-menthane-3,8-diol, a 2-methyl-2,4-pentanediol, a tetramethyl urea, an-methylpyrrolidone, an acetonitrile, a tetrahydrofuran (THF), adimethyl formamide (DMF), a N-methyl formamide (NMF), a dimethylsulfoxide (DMSO), a thionyl chloride and a sulfuryl chloride.

The diatom frustule portion may comprise a broken diatom frustuleportion. The diatom frustule portion may comprise an unbroken diatomfrustule portion. In some embodiments, the diatom frustule portion canbe obtained through a diatom frustule portion separation process. Forexample, the process may comprise at least one of using a surfactant toreduce an agglomeration of a plurality of diatom frustule portions andusing a disc stack centrifuge.

A method of forming zinc-oxide nanostructures on a diatom frustuleportion may include forming a zinc-oxide seed layer on a surface of thediatom frustule portion. The method may comprise forming a nanostructureon the zinc-oxide seed layer.

In some embodiments, the nanostructure can comprise at least one of ananowire, a nanoplate, a dense array of nanoparticles, a nanobelt, and ananodisk. In some embodiments, the nanostructures can comprisezinc-oxide.

Forming the zinc-oxide seed layer may comprise heating a first zinccontributing component and the diatom frustule portion. In someembodiments, heating the first zinc contributing component and thediatom frustule portion can comprise heating to a temperature in a rangefrom about 175° C. to about 225° C.

In some embodiments, forming the nanostructure can comprise applying aheating regimen to the diatom frustule portion having the zinc-oxideseed layer in the presence of a nanostructure forming solutioncomprising a second zinc contributing component. The heating regimen maycomprise heating to a nano structure forming temperature. For example,the nanostructure forming temperature may be from about 80° C. to about100° C. In some embodiments, the heating may be for a duration of aboutone to about three hours. In some embodiments, the heating regimen cancomprise applying a cyclic heating routine. For example, the cyclicheating routine may include applying a microwave heating to the diatomfrustule portion having the zinc-oxide seed layer for a heating durationand then turning the microwaving heating off for a cooling duration, fora total cyclic heating duration. In some embodiments, the heatingduration can be about 1 minute to about 5 minutes. In some embodiments,the cooling duration can be about 30 seconds to about 5 minutes. Thetotal cyclic heating duration may be about 5 minutes to about 20minutes. Applying the microwave heating may include applying about 480Watt to about 520 Watt of microwave power, including about 80 Watt toabout 120 Watt of microwave power.

In some embodiments, at least one of the first zinc contributingcomponent and the second zinc contributing component can comprise atleast one of a zinc acetate, a zinc acetate hydrate, a zinc nitrate, azinc nitrate hexahydrate, a zinc chloride, a zinc sulfate, and a sodiumzincate.

In some embodiments, the nanostructure forming solution may include abase. For example, the base may comprise at least one of a sodiumhydroxide, an ammonium hydroxide, potassium hydroxide, atetramethylammonium hydroxide, a lithium hydroxide, ahexamethylenetetramine, an ammonia solution, a sodium carbonate, and aethylenediamine.

In some embodiments, forming the nanostructure can comprise adding anadditive component. The additive component may include at least one of atributylamine, a triethylamine, a triethanolamine, a diisopropylamine,an ammonium phosphate, a 1,6-hexadianol, a triethyldiethylnol, anisopropylamine, a cyclohexylamine, a n-butylamine, an ammonium chloride,a hexamethylenetetramine, an ethylene glycol, an ethanolamine, apolyvinylalcohol, a polyethylene glycol, a sodium dodecyl sulphate, acetyltrimethyl ammonium bromide, and a carbamide.

In some embodiments, at least one of the nanostructure forming solutionand a zinc-oxide seed layer forming solution can comprise a solvent, thesolvent comprising at least one of a propylene glycol, a water, amethanol, an ethanol, a 1-propanol, a 2-propanol a 1-methoxy-2-propanol,a 1-butanol, a 2-butanol a 1-pentanol, a 2-pentanol, a 3-pentanol, a1-hexanol, a 2-hexanol, a 3-hexanol, an octanol, a 1-octanol, a2-octanol, a 3-octanol, a tetrahydrofurfuryl alcohol (THFA), acyclohexanol, a cyclopentanol, a terpineol, a butyl lactone; a methylethyl ether, a diethyl ether, an ethyl propyl ether, a polyethers, adiketones, a cyclohexanone, a cyclopentanone, a cycloheptanone, acyclooctanone, an acetone, a benzophenone, an acetylacetone, anacetophenone, a cyclopropanone, an isophorone, a methyl ethyl ketone, anethyl acetate, a dimethyl adipate, a propylene glycol monomethyl etheracetate, a dimethyl glutarate, a dimethyl succinate, a glycerin acetate,a carboxylates, a propylene carbonate, a glycerin, a diol, a triol, atetraol, a pentanol, an ethylene glycol, a diethylene glycol, apolyethylene glycol, a propylene glycol, a dipropylene glycol, a glycolether, a glycol ether acetate, a 1,4-butanediol, a 1,2-butanediol, a2,3-butanediol, a 1,3-propanediol, a 1,4-butanediol, a 1,5-pentanediol,a 1,8-octanediol, a 1,2-propanediol, a 1,3-butanediol, a1,2-pentanediol, an etohexadiol, a p-menthane-3,8-diol, a2-methyl-2,4-pentanediol, a tetramethyl urea, a n-methylpyrrolidone, anacetonitrile, a tetrahydrofuran (THF), a dimethyl formamide (DMF), aN-methyl formamide (NMF), a dimethyl sulfoxide (DMSO), a thionylchloride and a sulfuryl chloride.

The diatom frustule portion may comprise a broken diatom frustuleportion. The diatom frustule portion may comprise an unbroken diatomfrustule portion. In some embodiments, the diatom frustule portion canbe obtained through a diatom frustule portion separation process. Forexample, the process may comprise at least one of using a surfactant toreduce an agglomeration of a plurality of diatom frustule portions andusing a disc stack centrifuge.

A method of forming carbon nanostructures on a diatom frustule portionmay include forming a metal seed layer on a surface of the diatomfrustule portion. The method may include forming a carbon nanostructureon the seed layer.

In some embodiments, the carbon nanostructure can comprise a carbonnanotube. The carbon nanotube may comprise at least one of asingle-walled carbon nanotube and a multi-walled carbon nanotube.

In some embodiments, forming the metal seed layer can comprise spraycoating the surface of the diatom frustule portion. In some embodiments,forming the metal seed layer can comprise introducing the surface of thediatom frustule portion to at least one of a liquid comprising themetal, a gas comprising the metal and the solid comprising a metal.

In some embodiments, forming the carbon nanostructure can comprise usingchemical vapor deposition (CVD). Forming the carbon nanostructure cancomprise exposing the diatom frustule portion to a nanostructure formingreducing gas after exposing the diatom frustule portion to ananostructure forming carbon gas. Forming the carbon nanostructure maycomprise exposing the diatom frustule portion to a nanostructure formingreducing gas before exposing the diatom frustule portion to ananostructure forming carbon gas. In some embodiments, forming thecarbon nanostructure comprises exposing the diatom frustule portion to ananostructure forming gas mixture comprising a nanostructure formingreducing gas and a nanostructure forming carbon gas. The nanostructureforming gas mixture may include a neutral gas. For example, the neutralgas may be argon.

In some embodiments, the metal can comprise at least one of a nickel, aniron, a cobalt, a cobalt-molybdenum bimetallic, a copper, a gold, asilver, a platinum, a palladium, a manganese, an aluminum, a magnesium,a chromium, an antimony, an aluminum-iron-molybdenum (Al/Fe/Mo), an ironpentacarbonyl (Fe(CO)₅), an iron (III) nitrate hexahydrate((Fe(NO₃)₃·6H₂O), a cobalt (II) chloride hexahydrate (CoCl₂·6H₂O), anammonium molybdate tetrahydrate ((NH₄)₆Mo₇O₂₄·4H₂O), a molybdenum (VI)dichloride dioxide MoO₂Cl₂, and an alumina nanopowder.

In some embodiments, the nanostructure forming reducing gas can compriseat least one of an ammonia, a nitrogen, and a hydrogen. Thenanostructure forming carbon gas may comprise at least one of anacetylene, an ethylene, an ethanol, a methane, a carbon oxide, and abenzene.

In some embodiments, forming the metal seed layer can comprise forming asilver seed layer. Forming the silver seed layer may comprise forming asilver nanostructure on the surface of the diatom frustule portion.

The diatom frustule portion may comprise a broken diatom frustuleportion. The diatom frustule portion may comprise an unbroken diatomfrustule portion. In some embodiments, the diatom frustule portion canbe obtained through a diatom frustule portion separation process. Forexample, the process may comprise at least one of using a surfactant toreduce an agglomeration of a plurality of diatom frustule portions andusing a disc stack centrifuge.

A method of fabricating a silver ink may include combining anultraviolet light sensitive component and a plurality of diatom frustuleportions having a silver nanostructure on a surface of the plurality ofdiatom frustule portions, the surface comprising a plurality ofperforations.

In some embodiments, the method of fabricating the silver ink cancomprise forming a silver seed layer on the surface of the plurality ofdiatom frustule portions. In some embodiments, the method can includeforming the silver nanostructure on the seed layer.

The plurality of diatom frustule portions may include a plurality ofbroken diatom frustule portions. The plurality of diatom frustuleportions may include a plurality of diatom frustule flakes.

In some embodiments, the silver ink is depositable in a layer having athickness of about 5 microns to about 15 microns after curing. In someembodiments, at least one of the plurality of perforations has adiameter of about 250 nanometers to about 350 nanometers. In someembodiments, the silver nanostructure can comprise a thickness of about10 nanometers to about 500 nanometers. The silver ink may comprise anamount of diatom frustules within a range of about 50 weight percent toabout 80 weight percent.

Forming the silver seed layer may include forming the silver seed layeron a surface within the plurality of perforations to form a plurality ofsilver seed plated perforations. Forming the silver seed layer mayinclude forming the silver seed layer on substantially all surfaces ofthe plurality of diatom frustule portions.

In some embodiments, forming the silver nanostructure may compriseforming the silver nanostructure on a surface within the plurality ofperforations to form a plurality of silver nanostructure platedperforations. Forming the silver nanostructure may comprise forming thesilver nanostructure on substantially all surfaces of the plurality ofdiatom frustule portions.

In some embodiments, the ultraviolet light sensitive component can besensitive to an optical radiation having a wavelength shorter than adimension of the plurality of perforations. The ultraviolet lightsensitive component may be sensitive to an optical radiation having awavelength shorter than a dimension of at least one of the plurality ofsilver seed plated perforations and the plurality of silvernanostructure plated perforations.

In some embodiments, combining the plurality of diatom frustule portionswith the ultraviolet light sensitive component can include combining theplurality of diatom frustule portions with a photoinitiation synergistagent. For example, the photoinitiation synergist agent may comprise atleast one of an ethoxylated hexanediol acrylate, a propoxylatedhexanediol acrylate, an ethoxylated trimethylpropane triacrylate, atriallyl cyanurate and an acrylated amine.

In some embodiments, combining the plurality of diatom frustule portionswith the ultraviolet light sensitive component can include combining theplurality of diatom frustule portions with a photoinitiator agent. Thephotoinitiator agent may include at least one of a2-methyl-1-(4-methylthio)phenyl-2-morpholinyl-1-propanone and anisopropyl thioxanthone.

In some embodiments, combining the plurality of diatom frustule portionswith the ultraviolet light sensitive component can include combining theplurality of diatom frustule portions with a polar vinyl monomer. Forexample, the polar vinyl monomer may include at least one of an-vinyl-pyrrolidone and a n-vinylcaprolactam.

The method of fabricating the silver ink may comprise combining theplurality of diatom frustule portions with a rheology modifying agent.In some embodiments, the method of fabricating the silver ink cancomprise combining the plurality of diatom frustule portions with acrosslinking agent. In some embodiments, the method can includecombining the plurality of diatom frustule portions with a flow andlevel agent. In some embodiments, the method can include combining theplurality of diatom frustule portions with at least one of an adhesionpromoting agent, a wetting agent, and a viscosity reducing agent.

The silver nanostructure may include at least one of a coating, ananowire, a nanoplate, a dense array of nanoparticles, a nanobelt, and ananodisk.

In some embodiments, forming the silver seed layer can comprise applyinga cyclic heating regimen to a first silver contributing component andthe plurality of diatom frustule portions.

Forming the silver seed layer may comprise combining the diatom frustuleportion with a seed layer solution. For example, the seed layer solutionmay comprise the first silver contributing component and a seed layerreducing agent.

Forming the silver nanostructure may comprise combining the diatomfrustule portion with a nanostructure forming reducing agent. In someembodiments, forming the silver nanostructure can comprise heating thediatom frustule portion after combining the diatom frustule portion withthe nanostructure forming reducing agent. In some embodiments, formingthe silver nanostructure can comprise titrating the diatom frustuleportion with a titration solution comprising a nanostructure formingsolvent and a second silver contributing component.

In some embodiments, the plurality of diatom frustule portions can beobtained through a diatom frustule portion separation process. Forexample, the process may include at least one of using a surfactant toreduce an agglomeration of a plurality of diatom frustule portions andusing a disc stack centrifuge.

A conductive silver ink may include an ultraviolet light sensitivecomponent. The conductive ink may include a plurality of diatom frustuleportions having a silver nanostructure on a surface of the plurality ofdiatom frustule portions, the surface comprising a plurality ofperforations.

The plurality of diatom frustule portions may include a plurality ofbroken diatom frustule portions. The plurality of diatom frustuleportions may include a plurality of diatom frustule flakes.

In some embodiments, the silver ink is depositable in a layer having athickness of about 5 microns to about 15 microns (e.g., after curing).In some embodiments, at least one of the plurality of perforations has adiameter of about 250 nanometers to about 350 nanometers. In someembodiments, the silver nanostructure can comprise a thickness of about10 nanometers to about 500 nanometers. The silver ink may comprise anamount of diatom frustules within a range of about 50 weight percent toabout 80 weight percent.

In some embodiments, at least one of the plurality of perforations cancomprise a surface having a silver nanostructure.

In some embodiments, at least one of the plurality of perforationscomprises a surface having a silver seed layer. In some embodiments,substantially all surfaces of the plurality of diatom frustule portionscan comprise a silver nanostructure.

In some embodiments, the ultraviolet light sensitive component can besensitive to an optical radiation having a wavelength shorter than adimension of the plurality of perforations.

In some embodiments, the conductive silver ink can be curable by anultraviolet radiation. In some embodiments, the plurality ofperforations can have a dimension sufficient to allow the ultravioletradiation to pass through. The conductive silver ink may be depositablein a layer having a thickness of about 5 microns to about 15 microns(e.g., after curing).

In some embodiments, the conductive silver ink can be thermally curable.

The ultraviolet light sensitive component may include a photoinitiationsynergist agent. For example, the photoinitiation synergist agent maycomprise at least one of an ethoxylated hexanediol acrylate, apropoxylated hexanediol acrylate, an ethoxylated trimethylpropanetriacrylate, a triallyl cyanurate and an acrylated amine.

The ultraviolet light sensitive component may include a photoinitiatoragent. The photoinitiator agent may include at least one of a2-methyl-1-(4-methylthio)phenyl-2-morpholinyl-1-propanone and anisopropyl thioxanthone.

In some embodiments, the ultraviolet light sensitive component caninclude a polar vinyl monomer. For example, the polar vinyl monomer mayinclude at least one of a n-vinyl-pyrrolidone and a n-vinylcaprolactam.

The conductive silver ink may include at least one of a rheologymodifying agent, a crosslinking agent, a flow and level agent, aadhesion promoting agent, a wetting agent, and a viscosity reducingagent. In some embodimetns, the silver nanostructure can comprise atleast one of a coating, a nanowire, a nanoplate, a dense array ofnanoparticles, a nanobelt, and a nanodisk.

A method of fabricating a silver film may include curing a mixturecomprising an ultraviolet light sensitive component and a plurality ofdiatom frustule portions having a silver nanostructure on a surface ofthe plurality of diatom frustule portions, the surface comprising aplurality of perforations.

In some embodiments, the method of fabricating the silver film cancomprise forming a silver seed layer on the surface of the plurality ofdiatom frustule portions. In some embodiments, the method can compriseforming the silver nanostructure on the seed layer. In some embodiments,the method can include combining the plurality of diatom frustuleportions with the ultraviolet light sensitive component to form a silverink.

The plurality of diatom frustule portions may comprise a plurality ofbroken diatom frustule portions. The plurality of diatom frustuleportions may comprise a plurality of diatom frustule flakes.

In some embodiments, the silver ink is depositable in a layer having athickness of about 5 microns to about 15 microns (e.g., after curing).In some embodiments, at least one of the plurality of perforations has adiameter of about 250 nanometers to about 350 nanometers. In someembodiments, the silver nanostructure can comprise a thickness of about10 nanometers to about 500 nanometers. The silver ink may comprise anamount of diatom frustules within a range of about 50 weight percent toabout 80 weight percent.

Forming the silver seed layer may comprise forming the silver seed layeron a surface within the plurality of perforations to form a plurality ofsilver seed plated perforations. Forming the silver seed layer maycomprise forming the silver seed layer on substantially all surfaces ofthe plurality of diatom frustule portions.

Forming the silver nanostructure may comprise forming the silvernanostructure on a surface within the plurality of perforations to forma plurality of silver nanostructure plated perforations. Forming thesilver nanostructure may comprise forming the silver nanostructure onsubstantially all surfaces of the plurality of diatom frustule portions.

In some embodiments, curing the mixture can comprise exposing themixture to an ultraviolet light having a wavelength shorter than adimension of the plurality of perforations. In some embodiments, curingthe mixture can comprise exposing the mixture to an ultraviolet lighthaving a wavelength shorter than a dimension of at least one of theplurality of silver seed plated perforations and the plurality of silvernanostructure plated perforations.

In some embodiments, curing the mixture can comprise thermally curingthe mixture.

The ultraviolet light sensitive component may be sensitive to an opticalradiation having a wavelength shorter than a dimension of the pluralityof perforations. In some embodiments, the ultraviolet light sensitivecomponent can be sensitive to an optical radiation having a wavelengthshorter than a dimension of at least one of the plurality of silver seedplated perforations and the plurality of silver nanostructure platedperforations.

Combining the plurality of diatom frustule portions with the ultravioletlight sensitive component may comprise combining the plurality of diatomfrustule portions with a photoinitiation synergist agent. For example,the photoinitiation synergist agent may include at least one of anethoxylated hexanediol acrylate, a propoxylated hexanediol acrylate, anethoxylated trimethylpropane triacrylate, a triallyl cyanurate and anacrylated amine.

In some embodiments, combining the plurality of diatom frustule portionswith the ultraviolet light sensitive component can comprise combiningthe plurality of diatom frustule portions with a photoinitiator agent.The photoinitiator agent may include at least one of a2-methyl-1-(4-methylthio)phenyl-2-morpholinyl-1-propanone and anisopropyl thioxanthone.

In some embodiments, combining the plurality of diatom frustule portionswith the ultraviolet light sensitive component can comprise combiningthe plurality of diatom frustule portions with a polar vinyl monomer.The polar vinyl monomer may include at least one of an-vinyl-pyrrolidone and a n-vinylcaprolactam.

The method of fabricating the conductive silver ink may includecombining the plurality of diatom frustule portions with a rheologymodifying agent. In some embodiments, the method of fabricating theconductive silver ink can include combining the plurality of diatomfrustule portions with a crosslinking agent. In some embodiments, themethod can comprise combining the plurality of diatom frustule portionswith a flow and level agent. The method may include combining theplurality of diatom frustule portions with at least one of an adhesionpromoting agent, a wetting agent, and a viscosity reducing agent.

In some embodiments, the silver nanostructure can comprise at least oneof a coating, a nanowire, a nanoplate, a dense array of nanoparticles, ananobelt, and a nanodisk.

In some embodiments, forming the silver seed layer can comprise applyinga cyclic heating regimen to a first silver contributing component andthe plurality of diatom frustule portions.

Forming the silver seed layer may comprise combining the diatom frustuleportion with a seed layer solution. For example, the seed layer solutionmay comprise the first silver contributing component and a seed layerreducing agent.

Forming the silver nanostructure may comprise combining the diatomfrustule portion with a nanostructure forming reducing agent. In someembodiments, forming the silver nanostructure can comprise heating thediatom frustule portion after combining the diatom frustule portion withthe nanostructure forming reducing agent. In some embodiments, formingthe silver nanostructure can comprise titrating the diatom frustuleportion with a titration solution comprising a nanostructure formingsolvent and a second silver contributing component.

In some embodiments, the plurality of diatom frustule portions can beobtained through a diatom frustule portion separation process. Forexample, the process may include at least one of using a surfactant toreduce an agglomeration of a plurality of diatom frustule portions andusing a disc stack centrifuge.

A conductive silver film may include a plurality of diatom frustuleportions having a silver nanostructure on a surface of each of theplurality of diatom frustule portions, the surface comprising aplurality of perforations.

In some embodiments, the plurality of diatom frustule portions cancomprise a plurality of broken diatom frustule portion. The plurality ofdiatom frustule portions may include a plurality of diatom frustuleflakes.

In some embodiments, at least one of the plurality of perforations has adiameter of about 250 nanometers to about 350 nanometers. In someembodiments, the silver nanostructure can comprise a thickness of about10 nanometers to about 500 nanometers.

In some embodiments, at least one of the plurality of perforations cancomprise a surface having a silver nanostructure. In some embodiments,at least one of the plurality of perforations can comprise a surfacehaving a silver seed layer. Substantially all surfaces of the pluralityof diatom frustule portions may comprise a silver nanostructure.

In some embodiments, the silver nanostructure can comprise at least oneof a coating, a nanowire, a nanoplate, a dense array of nanoparticles, ananobelt, and a nanodisk.

In some embodiments, the conductive silver film can comprise a binderresin.

A printed energy storage device can include a first electrode, a secondelectrode, and a separator between the first electrode and the secondelectrode, where at least one of the first electrode and the secondelectrode can include a plurality of frustules havingmanganese-containing nanostructures.

In some embodiments, the frustules have a substantially uniformproperty, the substantially uniform property including at least one of afrustule shape, a frustule dimension, a frustule porosity, a frustulemechanical strength, a frustule material, and a degree of brokenness ofa frustule.

In some embodiments, the manganese-containing nanostructures can includean oxide of manganese. The oxide of manganese may includemanganese(II,III) oxide. The oxide of manganese may include manganeseoxyhydroxide.

In some embodiments, at least one of the first electrode and the secondelectrode can include frustules having zinc-oxide nanostructures. Thezinc-oxide nanostructures can include at least one of a nano-wire and anano-plate.

In some embodiments, the manganese-containing nanostructures coversubstantially all surfaces of the frustules. In some embodiments,manganese-containing nanostructures cover some surfaces of the frustulesand carbon-containing nanostructures cover other surfaces of thefrustules, the manganese-containing nanostructures interspersed with thecarbon-containing nanostructures.

A membrane of an energy storage device can include frustules havingmanganese-containing nanostructures.

In some embodiments, the manganese-containing nanostructures can includean oxide of manganese. The oxide of manganese may includemanganese(II,III) oxide. The oxide of manganese may include manganeseoxyhydroxide. In some embodiments, manganese-containing nanostructurescover some surfaces of the frustules and carbon-containingnanostructures cover other surfaces of the frustules, themanganese-containing nanostructures interspersed with thecarbon-containing nanostructures.

In some embodiments, at least some of the manganese-containingnanostructures can be a nano-fiber. In some embodiments, at least someof the manganese-containing nanostructures have a tetrahedral shape.

In some embodiments, the energy storage device includes a zinc-manganesebattery.

An ink for a printed film can include a solution, and frustules havingmanganese-containing nanostructures dispersed in the solution.

In some embodiments, the manganese-containing nanostructures can includean oxide of manganese. In some embodiments, the manganese-containingnanostructures can include at least one of MnO₂, MnO, Mn₂O₃, MnOOH, andMn₃O₄.

In some embodiments, at least some of the manganese-containingnanostructures can include a nano-fiber. In some embodiments, at leastsome of the manganese-containing nanostructures have a tetrahedralshape.

In some embodiments, manganese-containing nanostructures cover somesurfaces of the frustules and carbon-containing nanostructures coverother surfaces of the frustules, the manganese-containing nanostructuresinterspersed with the carbon-containing nano structures.

In some embodiments, an energy storage device can include a cathodehaving a first plurality of frustules, the first plurality of frustuleshaving nanostructures including an oxide of manganese; and an anodehaving a second plurality of frustules, the second plurality offrustules having nanostructures including zinc oxide. In someembodiments, the device can be a rechargeable battery.

In some embodiments, the oxide of manganese includes MnO. In someembodiments, the oxide of manganese includes at least one of Mn₃O₄,Mn₂O₃, and MnOOH.

In some embodiments, at least one of the first plurality of frustulesincludes a ratio of a mass of the oxide of manganese to a mass of the atleast one frustule of about 1:20 to about 20:1. In some embodiments, atleast one of the second plurality of frustules includes a ratio of amass of the zinc oxide to a mass of the at least one frustule of about1:20 to about 20:1.

In some embodiments, the anode can include an electrolyte salt. Theelectrolyte salt may include a zinc salt.

In some embodiments, at least one of the cathode and the anode caninclude carbon nanotubes. In some embodiments, at least one of thecathode and the anode can include a conductive filler. The conductivefiller may include graphite.

In some embodiments, the energy storage device can have a separatorbetween the cathode and the anode, where the separator includes a thirdplurality of frustules. The third plurality of frustules may havesubstantially no surface modifications.

In some embodiments, at least one of the cathode, the anode, and theseparator can include an ionic liquid.

In some embodiments, the first plurality of frustules having a firstplurality of pores substantially not occluded by the nanostructuresincluding the oxide of manganese, and where the second plurality offrustules has a second plurality of pores substantially not occluded bythe nanostructures including the zinc oxide.

In some embodiments, a frustule can include a plurality ofnanostructures on at least one surface, where the plurality ofnanostructures includes zinc oxide, and where a ratio of a mass of theplurality of nanostructures to a mass of the frustule is about 1:1 toabout 20:1. In some embodiments, the plurality of nanostructuresincludes at least one of nanowires, nanoplates, dense nanoparticles,nanobelts, and nanodisks. In some embodiments, the frustule includes aplurality of pores substantially not occluded by the plurality ofnanostructures.

In some embodiments, a frustule can include a plurality ofnanostructures on at least one surface, where the plurality ofnanostructures includes an oxide of manganese, and where a ratio of amass of the plurality of nanostructures to a mass of the frustule isabout 1:1 to about 20:1. In some embodiments, the oxide of manganeseincludes MnO. In some embodiments, the oxide of manganese includesMn₃O_(4.) In some embodiments, the oxide of manganese includes at leastone of Mn₂O₃ and MnOOH. In some embodiments, the plurality ofnanostructures includes at least one of nanowires, nanoplates, densenanoparticles, nanobelts, and nanodisks. In some embodiments, thefrustule includes a plurality of pores substantially not occluded by theplurality of nanostructures.

In some embodiments, an electrode of an energy storage device caninclude a plurality of frustules, where each of the plurality offrustules includes a plurality of nanostructures formed on at least onesurface, where at least one of the plurality of frustules has a ratio ofa mass of the plurality of nanostructures to a mass of the at least onefrustule of about 1:20 to about 20:1.

In some embodiments, the electrode can include carbon nanotubes. In someembodiments, the electrode can include a conductive filler. Theconductive filler may include graphite. In some embodiments, theelectrode can include an ionic liquid.

In some embodiments, each of the plurality of frustules includes aplurality of pores substantially not occluded by the plurality ofnanostructures.

The electrode may be an anode of the energy storage device. In someembodiments, the anode can include an electrolyte salt. In someembodiments, the electrolyte salt can include a zinc salt. In someembodiments, the plurality of nanostructures can include zinc oxide. Insome embodiments, the plurality of nanostructures can include at leastone of nanowires, nanoplates, dense nanoparticles, nanobelts, andnanodisks.

The electrode may be a cathode of the energy storage device. In someembodiments, the plurality of nanostructures can include an oxide ofmanganese. In some embodiments, the oxide of manganese can include MnO.In some embodiments, the oxide of manganese can include at least one ofMn₃O₄, Mn₂O₃ and MnOOH.

In some embodiments, an energy storage device can include a cathodehaving a first plurality of frustules, the first plurality of frustuleshaving nanostructures including an oxide of manganese; and an anodehaving a second plurality of frustules, the second plurality offrustules having nanostructures including zinc oxide. In someembodiments, the device can be a rechargeable battery. In someembodiments, at least one of the first plurality of frustules includes aratio of a mass of the oxide of manganese to a mass of the at least onefrustule of about 1:20 to about 100:1. In some embodiments, at least oneof the second plurality of frustules includes a ratio of a mass of thezinc oxide to a mass of the at least one frustule of about 1:20 to about100:1.

In some embodiments, a frustule can include a plurality ofnanostructures on at least one surface, where the plurality ofnanostructures includes zinc oxide, and where a ratio of a mass of theplurality of nanostructures to a mass of the frustule is about 1:1 toabout 100:1.

In some embodiments, a frustule can include a plurality ofnanostructures on at least one surface, where the plurality ofnanostructures includes an oxide of manganese, and where a ratio of amass of the plurality of nanostructures to a mass of the frustule isabout 1:1 to about 100:1.

In some embodiments, an electrode of an energy storage device caninclude a plurality of frustules, where each of the plurality offrustules includes a plurality of nanostructures formed on at least onesurface, where at least one of the plurality of frustules has a ratio ofa mass of the plurality of nanostructures to a mass of the at least onefrustule of about 1:20 to about 100:1.

In some embodiments, a supercapacitor comprises a pair of electrodes andan electrolyte comprising an ionic liquid, wherein at least one of theelectrodes comprises a plurality of frustules having formed thereon asurface active material.

In some embodiments, a supercapacitor comprises a pair of electrodescontacting an electrolyte, wherein at least one of the electrodescomprise a plurality of frustules and a zinc oxide.

In some embodiments, supercapacitor comprises a pair of electrodescontacting a non-aqueous electrolyte, wherein at least one of theelectrodes comprise a plurality of frustules and a manganese oxide.

In some embodiments, a method of fabricating a supercapacitor comprisesforming a separator between a pair of electrodes, wherein the separatorcomprises frustules, an electrolyte and a thermally conductive additive,wherein the thermally conductive additive is adapted to substantiallyabsorb a near infrared (NIR) radiation upon being applied to theseparator, thereby causing heating of the separator to acceleratedrying.

For purposes of summarizing the invention and the advantages achievedover the prior art, certain objects and advantages are described herein.Of course, it is to be understood that not necessarily all such objectsor advantages need to be achieved in accordance with any particularembodiment. Thus, for example, those skilled in the art will recognizethat the invention may be embodied or carried out in a manner that canachieve or optimize one advantage or a group of advantages withoutnecessarily achieving other objects or advantages.

All of these embodiments are intended to be within the scope of theinvention herein disclosed. These and other embodiments will becomereadily apparent to those skilled in the art from the following detaileddescription having reference to the attached figures, the invention notbeing limited to any particular disclosed embodiment(s).

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure are described with reference to the drawings of certainembodiments, which are intended to illustrate certain embodiments andnot to limit the invention.

FIG. 1 is a scanning electron microscope (SEM) image of diatomaceousearth comprising frustules.

FIG. 2 is a SEM image of an example frustule including a porous surface.

FIG. 3 is a SEM image of example frustules each having a substantiallycylindrical shape.

FIGS. 4A and 4B are a flow diagram of example steps of a frustuleseparation process.

FIG. 5A shows an example embodiment of a frustule comprising structureson both an exterior surface and an interior surface.

FIG. 5B shows a SEM image, at 50 k× magnification, of an examplefrustule surface seeded with silver.

FIG. 5C shows a SEM image, at 250 k× magnification, of a frustulesurface seeded with silver.

FIG. 5D shows a SEM image, at 20 k× magnification, of a frustule surfacehaving silver nanostructures formed thereon.

FIG. 5E shows a SEM image, at 150 k× magnification of a frustule surfacehaving silver nanostructures formed thereon.

FIG. 5F shows a SEM image, at 25 k× magnification, of a diatom frustuleflake having a surface coated by silver nanostructures.

FIG. 5G shows a SEM image, at 100 k× magnification, of a frustulesurface seeded with zinc-oxide.

FIG. 5H shows a SEM image, at 100 k× magnification, of a frustulesurface seeded with zinc-oxide.

FIG. 5I shows a SEM image, at 50 k× magnification, of a frustule surfacehaving zinc-oxide nanowires formed thereon.

FIG. 5J shows a SEM image, at 25 k× magnification, of a frustule surfacehaving zinc-oxide nanowires formed thereon.

FIG. 5K shows a SEM image, at 10 k× magnification, of a frustule surfacehaving zinc-oxide nanoplates formed thereon.

FIG. 5L shows a SEM image, at 50 k× magnification, of a frustule surfacehaving silver nanostructures formed thereon.

FIG. 5M shows a SEM image, at 10 k× magnification, of a frustule surfacehaving zinc-oxide nanowires formed thereon.

FIG. 5N shows a SEM image, at 100 k× magnification, of a frustulesurface having zinc-oxide nanowires formed thereon.

FIG. 5O shows a SEM image, at 500×magnification, of a plurality offrustules having zinc oxide nanostructures formed thereon.

FIG. 5P shows a SEM image, at 5 k× magnification, of a frustule havingzinc oxide nanostructures formed thereon.

FIG. 5Q shows a SEM image, at 20 k× magnification, of a frustule surfacehaving manganese oxide nanostructures formed thereon.

FIG. 5R shows a SEM image, at 50 k× magnification, of a frustule surfacehaving manganese oxide nanostructures formed thereon.

FIG. 5S shows a TEM image of manganese oxide nanocrystals formed on afrustule surface.

FIG. 5T shows an electron diffraction image of a manganese oxideparticle.

FIG. 5U shows a SEM image, at 10 k× magnification, of a frustule surfacehaving manganese-containing nano-fibers formed thereon.

FIG. 5V shows a SEM image, at 20 k× magnification, of a frustule havingmanganese oxide nanostructures formed thereon.

FIG. 5W shows a SEM image, at 50 k× magnification, of a cross-section ofan example frustule having manganese oxide nanostructures formedthereon.

FIG. 5X shows a SEM image, at 100 k× magnification, of a frustulesurface having manganese oxide nanostructures formed thereon.

FIG. 6 schematically illustrates an example embodiment of an energystorage device.

FIGS. 7A through 7E schematically illustrate examples of energy storagedevices during various steps of different fabrication processes.

FIG. 8 shows an example embodiment of a separator for an energy storagedevice incorporating frustules in a separator layer.

FIG. 9 shows an example embodiment of an electrode for an energy storagedevice incorporating frustules in an electrode layer.

FIG. 10 shows a graph of a discharge curve of an example energy storagedevice.

FIG. 11 shows a graph of the cycling performance of the energy storagedevice of FIG. 10 .

FIG. 12 shows a graph of an example charge-discharge performance of anenergy storage device.

FIG. 13 shows another graph of a charge-discharge performance of theenergy storage device of FIG. 12 .

FIG. 14A illustrates a cross-sectional view of a supercapacitor havingboth electrodes configured as a double-layer capacitor.

FIG. 14B illustrates a cross-sectional view of the supercapacitor ofFIG. 14A in operation, where a voltage is applied across the electrodes.

FIG. 15 illustrates a cross-sectional view of a supercapacitorcomprising an electrode that is configured as a pseudo capacitor.

FIGS. 16A and 16B illustrate experimental charge/discharge measurementsperformed on a supercapacitor having symmetric printed electrodes, whereeach of the electrodes having opposite polarities comprises frustuleshaving formed thereon zinc oxide (Zn_(x)O_(y)) nanostructures.

FIGS. 17A-17D illustrate experimental charge/discharge measurementsperformed on a supercapacitor having symmetric printed electrodes, whereeach of the electrodes having opposite polarities comprises frustuleshaving formed thereon manganese oxide (Mn_(x)O_(y)) nanostructures.

FIGS. 18A-18E illustrate experimental charge/discharge measurementsperformed on a supercapacitor having asymmetric printed electrodes,where one of the electrodes having opposite polarities comprisesfrustules having formed thereon manganese oxide (Mn_(x)O_(y))nanostructures, while the other of the electrodes comprises frustuleshaving formed thereon CNT.

FIGS. 19A-19B illustrate experimental charge/discharge measurementsperformed on a supercapacitor having symmetric printed electrodes, whereeach of the electrodes having opposite polarities comprises frustuleshaving formed thereon CNT.

DETAILED DESCRIPTION

Although certain embodiments and examples are described below, those ofskill in the art will appreciate that the invention extends beyond thespecifically disclosed embodiments and/or uses and obvious modificationsand equivalents thereof. Thus, it is intended that the scope of theinvention herein disclosed should not be limited by any particularembodiments described below.

Energy storage devices used to power electronic devices generallyinclude batteries (e.g., rechargeable batteries), capacitors, andsuper-capacitors (e.g., EDLCs, pseudo capacitors and hybridsupercapacitors). Energy storage devices may comprise an asymmetricenergy storage device, including, for example, a battery-capacitorhybrid. Energy storage devices can be manufactured using printingtechnologies such as screen printing, roll-to-roll printing, ink-jetprinting, etc. Printed energy storage devices can facilitate reducedenergy storage device thickness, enabling compact energy storage.Printed energy storage devices can enable increased energy storagedensity by facilitating, for example, stacking of the energy storagedevices. Increased energy storage density may facilitate use of printedenergy storage devices for applications having a large powerrequirement, such as solar energy storage. Unlike energy storage deviceshaving a rigid outer casing, printed energy storage devices may beimplemented on a flexible substrate, enabling a flexible energy storagedevice. A flexible energy storage device can facilitate fabrication offlexible electronic devices, such as flexible electronic display media.Due to reduced thickness and/or flexible structure, printed energystorage devices may power cosmetic patches, medical diagnostic products,remote sensor arrays, smartcards, smart packaging, smart clothing,greeting cards, etc.

Reliability and durability of a printed energy storage device may be afactor hindering increased adoption of printed batteries. Printed energystorage devices typically lack a rigid outer casing, so printed energystorage devices may not stand up well to compressive pressure or shapedeforming manipulation in use or production. Variation of an energystorage device layer thickness in response to compressive pressure orshape deforming manipulation may adversely affect device reliability.For example, some printed energy storage devices include electrodesspaced by a separator. Deviations in separator thickness may cause ashort between the electrodes, such as when a separator is compressibleand fails to maintain a separation between the electrodes undercompressive pressure or shape deforming manipulation.

Costs associated with fabricating a printed energy storage device mayalso be a factor hampering use of printed energy storage devices topower a wider range of applications. Reliable fabrication of energystorage devices using printing technologies may facilitatecost-effective energy storage device production. Printing of an energystorage device may enable integrating the device printing process intothe production of electronic devices, including for example printedelectronic devices powered by the printed energy storage device,possibly enabling further cost savings. However, inadequate devicestructural robustness may hinder device integrity throughout thefabrication process, decreasing the feasibility of some printingtechnologies and impeding cost-effective production of the printedenergy storage devices. Thickness of a printed energy storage devicelayer may also impede the use of certain printing technologies in thefabrication process, for example due to a device layer thickness that isgreater than a film thickness at which the printing technology caneffectively print.

As described herein, frustules may have significant mechanical strengthor resistance to shear stress, for example due to dimensions, shape,porosity, and/or material. According to some implementations describedherein, an energy storage device includes one or more components, forexample one or more layers or membranes of a printed energy storagedevice, comprising frustules. An energy storage device comprisingfrustules may have mechanical strength and/or structural integrity suchthat the energy storage device is able to withstand compressive pressureand/or shape deforming manipulation, which can occur during manufactureor use, without failure, such that device reliability can increase. Anenergy storage device comprising frustules can resist variations inlayer thicknesses, enabling maintenance of uniform or substantiallyuniform device layer thicknesses. For example, a separator comprisingfrustules may withstand compressive pressure or shape deformingmanipulation to thereby facilitate improved energy storage devicereliability by maintaining a uniform or substantially uniform separationdistance between electrodes to inhibit or prevent a short in the device.

Increased mechanical strength in energy storage devices comprisingfrustules may facilitate reliable fabrication of the energy storagedevices using various printing technologies, thereby enablingcost-effective device fabrication due to increased yield and/orintegration of the fabrication process with the production process ofapplications powered by the devices.

Energy storage devices may be printed using an ink comprising frustules.For example, one or more membranes of a printed energy storage devicemay comprise frustules. One or more membranes of a printed energystorage device having frustules may be reliably printed onto a varietyof substrates, including but not limited to, a flexible or inflexiblesubstrate, a textile, a device, a plastic, any variety of films such asa metallic or semiconductor film, any variety of paper, combinationsthereof, and/or the like. For example, suitable substrates may includegraphite paper, graphene paper, polyester film (e.g., Mylar),polycarbonate film aluminum foil, copper foil, stainless steel foil,carbon foam, combinations thereof, and/or the like. Fabrication ofprinted energy storage devices on flexible substrates may allow forflexible printed energy storage devices that can be used in a wide arrayof devices and implementations due to increased reliability of certainsuch printed energy storage devices, for example due to increasedrobustness as a result of one or more layers comprising frustules.

Improved mechanical strength in printed energy storage devicescomprising frustules may also enable a reduced printed device layerthickness. For example, frustules may provide structural support for anenergy storage device layer, enabling thinner layers having sufficientstructural robustness to withstand compressive pressure or shapedeforming manipulation, which can then reduce an overall devicethickness. Decreased thickness of printed energy storage devices canfurther facilitate energy storage density of the printed devices and/orenable wider use of the printed devices.

A printed energy storage device comprising frustules may have improveddevice performance, for example improved device efficiency. Reducedthickness of an energy storage device layer may enable improved deviceperformance. Performance of an energy storage device may depend at leastin part on the internal resistance of the energy storage device. Forexample, performance of an energy storage device may depend at least inpart on a separation distance between a first and a second electrode. Adecreased separator membrane thickness for a given measure ofreliability reduces a distance between a first and a second electrode,which can reduce the internal resistance and improve an efficiency ofthe energy storage device. Internal resistance of an energy storagedevice may also depend at least in part on the mobility of ionic speciesbetween a first and a second electrode. Porosity of frustule surfacesmay enable mobility of ionic species. For example, a separatorcomprising frustules may enable a more structurally robust separationbetween electrodes of an energy storage device while facilitatingmobility of ionic species between the electrodes. Frustule surfaceporosity may facilitate a direct path for mobile ionic species between afirst electrode and a second electrode, reducing a resistance and/orincreasing efficiency. Reduced thickness of an electrode layercomprising frustules and porosity of the electrode frustules may alsoenable improved storage device performance. A reduced electrodethickness may provide increased access of ionic species to activematerials within the electrode. Porosity and/or conductivity offrustules in an electrode may facilitate mobility of the ionic specieswithin the electrode. Frustules in an electrode may also enable improveddevice performance by, for example, serving as a substrate on whichactive materials and/or structures comprising active materials may beapplied or formed, enabling increased surface area for active materialsand thereby facilitating access of ionic species to the activematerials.

FIG. 1 is a SEM image of diatomaceous earth comprising frustules 10. Thefrustules 10 have a generally cylindrical shape, although some frustulesare broken or differently shaped. In some embodiments, the cylindricalfrustules 10 have a diameter between about 3 μm and about 5 μm. In someembodiments, the cylindrical frustules 10 have a length between about 10μm and about 20 μm. Other diameters and/or lengths are also possible.The frustules 10 may have significant mechanical strength or resistanceto shear stress, for example due to architecture (e.g., dimensions,shape), material, combinations thereof, and/or the like. For example,mechanical strength of a frustule 10 may be inversely related to thesize of the frustule 10. In some embodiments, a frustule 10 having alongest axis in a range of from about 30 μm to about 130 μm canwithstand compressive forces from about 90 μN to about 730 μN.

FIG. 2 is a SEM image of an example frustule 10 including a poroussurface 12. The porous surface 12 includes circular or substantiallycircular openings 14. Other shapes of the openings 14 are also possible(e.g., curved, polygonal, elongate, etc.). In some embodiments, theporous surface 12 of a frustule 10 has a uniform or substantiallyuniform porosity, for example including openings 14 having uniform orsubstantially uniform shape, dimensions, and/or spacing (e.g., as shownin FIG. 2 ). In some embodiments, the porous surface 12 of a frustule 10has a varying porosity, for example including openings 14 havingdifferent shapes, dimensions, and/or spacing. The porous surfaces 12 ofa plurality of frustules 10 can have uniform or substantially uniformporosities, or porosity of the porous surfaces 12 of different frustules10 may vary. A porous surface 12 may comprise nanoporosity, includingfor example microporosity, mesoporosity, and/or macroporosity.

FIG. 3 is a SEM image of example frustules 10 each having a cylindricalor substantially cylindrical shape. Frustule features may differ amongdifferent species of diatoms, each diatom species having frustules of adifferent shape, size, porosity, material, and/or another frustuleattribute. Diatomaceous earth, which may be commercially available(e.g., from Mount Sylvia Diatomite Pty Ltd of Canberra, Australia,Continental Chemical USA of Fort Lauderdale, Fla., Lintech InternationalLLC of Macon, Ga., etc.), can serve as a source of frustules. In someembodiments, diatomaceous earth is sorted according to a pre-determinedfrustule feature. For example, sorting may result in frustules eachincluding a predetermined feature, such as shape, dimensions, material,porosity, combinations thereof, and/or the like. Sorting frustules mayinclude one or a variety of separation processes such as, for example,filtering, screening (e.g., use of vibrating sieves for separationaccording to a frustule shape or size), a separation process involvingvoraxial or centrifugal technology (e.g., for separation according tofrustule density), any other suitable solid-solid separation processes,combinations thereof, and/or the like. Frustules may also be available(e.g., from a commercial source) already sorted according to a frustulefeature such that the frustules already comprise a uniform orsubstantially uniform shape, size, material, porosity, anotherpre-determined frustule attribute, combinations thereof, and/or thelike. For example, frustules available from a geographic region (e.g., aregion of a country such as the United States, Peru, Australia, etc.; aregion of the globe; etc.) and/or a type of natural environment (e.g.,freshwater environment, saltwater environment, etc.) may comprisefrustules of a species typically found in that geographic region and/orenvironment, providing frustules having a uniform or substantiallyuniform shape, size, material, porosity, another pre-determined frustuleattribute, combinations thereof, and/or the like.

In some embodiments, a separation process can be used to sort frustulessuch that only or substantially only unbroken frustules are retained. Insome embodiments, the separation process can be used to remove broken orsmall frustules, resulting in only or substantially onlycylindrically-shaped frustules 10 having certain lengths and/ordiameters (e.g., as illustrated in FIG. 3 ). The separation process toremove broken frustules may include screening, such as with the use of asieve having a mesh size selected to retain only or substantially onlyfrustules having a pre-determined dimension. For example, the mesh sizeof the sieve may be selected to remove frustules having a dimension(e.g., a length or diameter) of no more than about 40 μm, no more thanabout 30 μm, no more than about 20 μm or no more than about 10 μm, andincluding ranges bordering and including the foregoing values. Othersieve mesh sizes may also be suitable.

In some embodiments, the separation process to remove broken frustulesincludes application of ultrasonic waves to frustules placed in a fluiddispersion, including for example ultrasonication during which frustulesdispersed in a water bath are subjected to ultrasonic waves. Sonicationparameters such as power, frequency, duration, and/or the like may beadjusted based at least in part on one or more attributes of thefrustules. In some embodiments, ultrasonication includes use of soundwaves having a frequency between about 20 kilohertz (kHz) and about 100kHz, between about 30 kHz and about 80 kHz, and between about 40 kHz andabout 60 kHz. In some embodiments, ultrasonication may use sound waveshaving a frequency of about 20 kHz, about 25 kHz, about 30 kHz, about 35kHz, about 40 kHz, about 45 kHz, and ranges bordering and including theforegoing values. The ultrasonication step may have a duration betweenabout 2 minutes and about 20 minutes, between about 2 minutes and about15 minutes, and between about 5 minutes and about 10 minutes. In someembodiments, ultrasonication step may have a duration of about 2minutes, about 5 minutes, about 10 minutes, and ranges bordering andincluding the foregoing values. For example, a frustule-fluid sample maybe subjected to ultrasonic waves at a frequency of about 35 kHz for aduration of about 5 minutes.

In some embodiments, separation process includes sedimentation. Forexample, the separation process may include both ultrasonication andsedimentation such that heavier particles from the frustule-fluid samplemay be allowed to settle out from the suspended phase of thefrustule-fluid sample during ultrasonication. In some embodiments, thesedimentation process of heavier particles from the frustule-fluidsample has a duration between about 15 seconds and about 120 seconds,between about 20 seconds and about 80 seconds, and between about 30seconds and about 60 seconds. In some embodiments, sedimentation has aduration of no more than about 120 seconds, no more than about 60seconds, no more than about 45 seconds, no more than or about 30seconds.

The separation process to remove broken frustules may include use ofhigh-velocity centrifugal technology for physical separation based ondensity, including for example an ultracentrifugation step. For example,the separation process may include ultracentrifugation of the suspendedphase of a frustule-fluid sample. Ultracentrifugation parameters such asangular velocity, duration, and/or the like may depend at least in parton the composition of the suspended phase (e.g., a density of thefrustules) and/or characteristics of the equipment used. For example,the suspended phase may be ultracentrifuged at an angular velocitybetween about 10,000 rotations per minute (RPM) and about 40,000 RPM,between about 10,000 RPM and about 30,000 RPM, between about 10,000 RPMand about 20,000 RPM, and between about 10,000 RPM and about 15,000 RPM.The suspended phase may be ultracentrifuged for a duration between about1 minute and about 5 minutes, between about 1 minute and about 3minutes, and between about 1 minute and about 2 minutes. For example,the suspended phase of the frustule-fluid sample may be ultracentrifugedat an angular velocity of about 13,000 RPM for about 1 minute.

FIGS. 4A and 4B are a flow diagram of example steps of a frustuleseparation process 20. The process 20 may enable separation of brokenand/or unbroken diatom frustules from a solid mixture comprising, forexample, broken and unbroken diatom frustules. In some embodiments, theseparation process 20 enables large scale frustule sorting.

As described herein, there can be two sources of diatom frustules fornanostructured materials and/or nanodevices: living diatoms anddiatomaceous earth. Diatoms can be taken directly from nature orcultured. Artificially, a large number of identical silica frustules canbe cultured within a few days. To use natural diatoms for nanostructuredmaterials and/or nanodevices, a separation process can be performed toseparate the diatoms from other organic materials and/or substances.Another approach is to use diatomaceous earth. The sediments areabundant and the material is of low cost.

Diatomaceous earth can have frustules ranging from mixtures of differentdiatom species to a single diatom species (e.g., including somefreshwater sediments). Diatomaceous earth can comprise broken and/orwhole diatom frustules plus contaminating materials of different origin.Depending on application, one may use only whole diatom frustules, onlybroken frustules, or a mixture of both. For example, when separatingwhole frustules, diatomaceous earth with one kind of frustules may beused.

In some embodiments, a method of separating comprises separating wholediatom frustules from broken pieces of diatom frustules. In someembodiments, the separation process comprises sorting whole diatomfrustules according to a common frustule characteristic (e.g., adimension including a length or diameter, a shape, and/or a material)and/or sorting portions of diatom frustules based on a common frustulecharacteristic (e.g., a dimension including a length or diameter, ashape, degree of brokenness, and/or a material). For example, theseparation process may enable extracting a plurality of diatom frustulesor portions of diatom frustules having at least one commoncharacteristic. In some embodiments, the separation process comprisesremoving contaminative material having a different chemical origin fromthe diatom frustules and/or portions of diatom frustules.

Diatoms and diatom frustules that stay unchanged during long timeperiods are sometimes used in biological, ecological, and related earthscience research. Many approaches have been developed to extract smallsamples of frustules from water or sediments. The sediments(diatomaceous earth) contain diatom frustules (broken and unbroken)alongside with carbonates, mica, clay, organics and other sedimentaryparticles. The separation of unbroken frustules may involve three mainsteps: removal of organic remains, removal of particles with differentchemical origin, and removal of broken pieces. The removal of organicmatter may be realized with heating of samples in a bleach (e.g.,hydrogen peroxide and/or nitric acid), and/or annealing at highertemperatures. The carbonates, clay, and other soluble non-silicamaterials may be removed by hydrochloric and/or sulfuric acid. For theseparation of broken and unbroken frustules, several techniques can beapplied: sieving, sedimentation and centrifugation, centrifugation witha heavy liquid, and split-flow lateral-transport thin separation cells,and combinations thereof. A problem for all of these approaches mayoften be aggregation of broken and unbroken frustules, which candiminish the quality of the separation, and/or may render the separationprocess suitable only for laboratory size samples.

Scaling up separation procedures may enable diatom frustules to be usedas industrial nanomaterials.

In some embodiments, a separation procedure that can be utilized forindustrial scale separation of diatoms comprises separation of diatomfrustule portions having at least one common characteristic. Forexample, the common characteristic could be unbroken diatom frustules orbroken diatom frustules. The separation process 20, as shown in FIGS. 4Aand 4B, is an example separation procedure enabling industrial scaleseparation of diatoms. In some embodiments, a separation procedure thatenables large scale separation of diatoms enables a reduction in theagglomeration of frustules, such as by using a surfactant and/or a discstack centrifuge. In some embodiments, use of the surfactant can enablethe large scale separation. In some embodiments, using the disc stackcentrifuge (e.g., a milk separator type centrifugation process) canenable large scale separation. For example, use of the surfactant todisperse diatom frustules together with a disc stack centrifuge to sortfrustules based on a frustule characteristic may facilitate large scaleseparation of diatoms by enabling reduced agglomeration of the diatomfrustules. A traditional, non-disk stack centrifuge process would causesedimentation of the frustules. The supernatant fluid would bediscarded, and the sedimented frustules would be redispersed in asolvent, after which the centrifuge would again cause sedimentation ofthe frustules. This process would be repeated until the desiredseparation is achieved. A disk stack centrifuge process can continuouslyredisperse and separate sedimented frustules. For example, a phaseenriched with whole diatoms can be continuously circulated through thedisk stack centrifuge, becoming more and more enriched. In someembodiments, the disc stack centrifuge can enable a separation of brokendiatom frustules from unbroken diatom frustules. In some embodiments,the disc stack centrifuge can enable a sorting of the diatom frustulesaccording to a diatom frustule characteristic. For example, the discstack centrifuge may enable extraction of frustules having at least onecommon characteristic (e.g., a dimension, a shape, a degree ofbrokenness and/or a material).

A separation procedure enabling industrial scale separation of diatoms,such as the separation process 20 shown in FIGS. 4A and 4B, may includethe following steps:

1. Particles of a solid mixture (e.g., diatomaceous earth) comprisingthe diatom frustules and/or portions of diatom frustules may be rockyand can be broken down into smaller particles. For example, a particlesize of the solid mixture may be reduced to facilitate the separationprocess 20. In some embodiments, to obtain a powder, the diatomaceousearth can be mildly milled or ground, for example using a mortar andpestle, a jar mill, a rock crusher, combinations thereof, and/or thelike.

2. In some embodiments, components of the diatomaceous earth that arelarger than the diatom frustules or portions of diatom frustules may beremoved through a sieving step. In some embodiments, the sieving step isperformed after the diatomaceous earth has been milled. For example,diatomaceous earth powder may be sieved to remove the particles of thepowder which are bigger than the frustules. In some embodiments, thesieving can be facilitated by dispersing the solid mixture (e.g., milleddiatomaceous earth) in a liquid solvent. The solvent may be water,and/or other suitable liquid solvents. Dispersing the solid mixture inthe solvent may be facilitated by sonicating the mixture comprising thesolid mixture and the solvent. Other methods of aiding dispersion mayalso be suitable. In some embodiments, the dispersion comprises a weightpercent of diatoms within a range of from about 1 weight percent toabout 5 weight percent, about 1 weight percent to about 10 weightpercent, about 1 weight percent to about 15 weight percent, or about 1weight percent to about 20 weight percent. A concentration of the solidmixture in the dispersion may be reduced to facilitate the sieving stepto remove particles of the dispersion that are larger than the diatoms.The sieve openings depend on the size of diatoms in the sample. Forexample, a suitable sieve may comprise a mesh size of about 20 microns,or any other mesh size that enables removal from the dispersionparticles of the solid mixture that are larger than the diatoms (e.g., asieve having a mesh size of about 15 microns to about 25 microns, or ofabout 10 microns to about 25 microns). A shaker sieve may be used foreffectively increasing flow through the sieve.

3. In some embodiments, the separation process includes a purificationstep to remove organic contaminants from the diatoms (e.g., diatomfrustules or portions of diatom frustules). A suitable process forremoving organic contaminants may comprise immersing and/or heating thediatoms in a bleach (e.g., nitric acid and/or hydrogen peroxide), and/orannealing the diatoms at higher temperatures. For example, a sample ofdiatoms may be heated in a volume of a solution comprising about 10volume percent to about 50 volume percent (e.g., 30 volume percent)hydrogen peroxide for about 1 minute to about 15 minutes (e.g., 10minutes). Other compositions, concentrations and/or durations may besuitable. For example, the composition of the solution used, theconcentration of the solution used, and/or the duration of the heatingmay depend on the composition of the sample to be purified (e.g., typesof organic contaminants and/or diatoms). In some embodiments, thediatoms can be heated in a solution until the solution ceases orsubstantially ceases to bubble (e.g., indicating removal of organiccontaminants is complete or substantially complete) to facilitatesufficient removal of the organic contaminants. Immersing and/or heatingdiatoms in a solution may be repeated until organic contaminants havebeen removed or substantially removed.

Purification of diatoms from organic contaminants may be followed bywashing with water. In some embodiments, the diatoms may be washed witha liquid solvent (e.g., water). The diatoms may be separated from thesolvent through a sedimentation process, including for example acentrifuge step. Suitable centrifuge technology may include, forexample, a disc stack centrifuge, a decanter centrifuge, a tubular bowlcentrifuge, combinations thereof, and/or the like.

4. In some embodiments, the separation process includes a purificationstep to remove inorganic contaminants. Inorganic contaminants may beremoved by mixing the diatoms with hydrochloric and/or sulfuric acid.Inorganic contaminants may include carbonates, clay, and other solublenon-silica materials. For example, a sample of diatoms may be mixed witha volume of solution comprising about 15 volume percent to about 25volume percent of hydrochloric acid (e.g., about 20 volume percenthydrochloric acid) for a duration of about 20 minutes to about 40minutes (e.g., about 30 minutes). Other compositions, concentrationsand/or durations may be suitable. For example, the composition of thesolution used, the concentration of the solution used, and/or theduration of the mixing may depend on the composition of the sample to bepurified (e.g., types of inorganic contaminants and/or diatoms). In someembodiments, the diatoms can be mixed in a solution until the solutionceases or substantially ceases to bubble (e.g., indicating removal ofinorganic contaminants is complete or substantially complete) tofacilitate sufficient removal of the inorganic contaminants. Mixingdiatoms with a solution may be repeated until inorganic contaminantshave been removed or substantially removed.

Purification of diatoms from soluble inorganic contaminants may befollowed by washing with water. In some embodiments, the diatoms may bewashed with a liquid solvent (e.g., water). The diatoms may be separatedfrom the solvent through a sedimentation process, including for examplea centrifuge step. Suitable centrifuge technology may include, forexample, a disc stack centrifuge, a decanter centrifuge, a tubular bowlcentrifuge, combinations thereof, and/or the like.

5. In some embodiments, the separation process comprises dispersing offrustules in a surfactant. The surfactant may facilitate separation ofthe frustules and/or portions of frustules from one another, reducingagglomeration of the frustules and/or portions of frustules. In someembodiments, an additive is used to reduce agglomeration of the diatoms.For example, diatoms may be dispersed in a surfactant and an additive.In some embodiments, dispersing of the diatoms in the surfactant and/oradditive may be facilitated by sonicating the mixture comprisingdiatoms, the surfactant and/or the additive.

6. In some embodiments, broken frustule pieces may be extracted by a wetsieving process. For example, a filtering process may be used. In someembodiments, the filtering process comprises using a sieve for removingthe smaller pieces of broken frustules. The sieve may comprise a meshsize suitable for removing the smaller pieces of broken frustules (e.g.,a 7 micron sieve). The wet sieving process can inhibit or prevent smallsediment from accumulating in the pores of the sieve and/or allow smallparticles to pass through the pores of the sieve, for example bydisturbing agglomeration of the sediment. Disturbing agglomeration mayinclude, for example, stirring, bubbling, shaking, combinations thereof,and the like of materials which sediment on the sieve mesh. In someembodiments, the filtering process can be continuous through a series ofsieves (e.g., having increasingly smaller pores or mesh sizes) (e.g.,multiple sieves in a machine having a single input and output).

7. In some embodiments, a continuous centrifugation (milk separator—typemachine) of frustules in a liquid can be used. For example, a disc stackcentrifuge may be used. This process may be used to separate the diatomsaccording to a common characteristic, including for example, furtherseparating broken frustule pieces from the unbroken frustules. In someembodiments, disc stack centrifuge step can be repeated to achieve adesired separation (e.g., desired level of separation of the brokenfrustules from the unbroken frustules).

8. As described herein, frustules may be washed in solvent, followed bya sedimentation process (e.g. centrifugation) in order to extract thefrustules from the solvent. For example, centrifugation can be used tosediment frustules or portions of frustules after each washing stepand/or before final use. Suitable centrifuge technology for sedimentingfrustules after a wash step may include continuous centrifuges,including but not limited to a disc stack centrifuge, a decantercentrifuge, and/or a tubular bowl centrifuge.

The example separation procedure has been tested with fresh waterdiatoms from Mount Silvia Pty, Ltd. Diatomite mining company,Queensland, Australia. The majority of frustules in the sample has onekind of diatoms Aulacoseira sp. The frustules have cylindrical shapewith diameter of about 5 microns and length from 10 to 20 microns.

Flow-chart of an example separation procedure, separation process 20presented in FIGS. 4A and 4B only serves as an example. The quantitiesof parameters in the flowchart are provided as illustrative examples(e.g., suited to the chosen sample only). For example, quantities may bedifferent for different types of diatoms.

The surface of diatoms can include amorphous silica and can includesilanol groups, which are negatively charged. Isoelectric point foundfrom zeta potential measurements can often be around pH₂ for diatoms(e.g., similar to that of amorphous silica).

In some embodiments, the surfactant can comprise a cationic surfactant.Suitable cationic surfactants can include benzalkonium chloride,cetrimonium bromide, lauryl methyl gluceth-10 hydroxypropyl dimoniumchloride, benzethonium chloride, benzethonium chloride, bronidox,dimethyldioctadecylammonium chloride, tetramethylammonium hydroxide,mixtures thereof, and/or the like. The surfactant may be a nonionicsurfactant. Suitable nonionic surfactants can include: cetyl alcohol,stearyl alcohol, and cetostearyl alcohol, oleyl alcohol, polyoxyethyleneglycol alkyl ethers, octaethylene glycol monododecyl ether, glucosidealkyl ethers, decyl glucoside, polyoxyethylene glycol octylphenolethers, Triton X-100, Nonoxynol-9, glyceryl laurate, polysorbate,poloxamers, mixtures thereof, and/or the like.

In some embodiments, one or more additives can be added to reduceagglomeration. Suitable additives may include: potassium chloride,ammonium chloride, ammonium hydroxide, sodium hydroxide, mixturesthereof, and/or the like.

Frustules may have one or more modifications applied to a surface of thefrustules. In some embodiments, frustules may be used as a substrate toform one or more structures on one or more surfaces of the frustules.FIG. 5A shows an example frustule 50 comprising structures 52. Forexample, a frustule 50 may have a hollow cylindrical or substantiallycylindrical shape, and may comprise structures 52 on both an exteriorand interior surface of the cylinder. The structures 52 may modify oraffect a characteristic or attribute of the frustule 50, including, forexample, the conductivity of the frustule 50. For example, anelectrically insulating frustule 50 may be made electrically conductiveby forming electrically conductive structures 52 on one or more surfacesof the frustule 50. A frustule 50 may include structures 52 comprisingsilver, aluminum, tantalum, brass, copper, lithium, magnesium,combinations thereof, and/or the like. In some embodiments, a frustule50 includes structures 52 comprising ZnO. In some embodiments, afrustule 50 includes structures 52 comprising an oxide of manganese,such as manganese dioxide (MnO₂), manganese (II, III) oxide (Mn₃O₄),manganese (II) oxide (MnO), manganese (III) oxide (Mn₂O₃), and/ormanganese oxyhydroxide (MnOOH). In some embodiments, a frustule 50includes structures 52 comprising other metal-containing compounds oroxides. In some embodiments, a frustule 50 includes structures 52comprising a semiconductor material, including silicon, germanium,silicon germanium, gallium arsenide, combinations thereof, and/or thelike. In some embodiments, frustules 50 comprise surface modifyingstructures 52 on all or substantially all of the surfaces of thefrustules 50.

Structures 52 applied or formed on a surface of a frustule 50 maycomprise various shapes, dimensions, and/or other attributes. A frustule50 may comprise structures 52 having a uniform or substantially uniformshape, dimension, and/or another structure 52 attribute. In someembodiments, a frustule 50 may have structures 52 comprising nanowires,nanotubes, nanosheets, nanoflakes, nanospheres, nanoparticles,structures having a rosette shape, combinations thereof, and/or thelike. In some embodiments, a nanostructure can have a dimension having alength of about 0.1 nanometers (nm) to about 1000 nm. In someembodiments, the dimension is a diameter of the nanostructure. In someembodiments, the dimension is a longest dimension of the nanostructure.In some embodiments, the dimension is a length and/or width of thenanostructure. Nanostructures on surfaces of frustules may facilitatematerials having increased surface area, advantageously providingmaterials having increased surface area on which electrochemicalreaction can occur. In some embodiments, diatom frustules can reduce,prevent, or substantially prevent agglomeration of nanostructures inmanufacturing processes and/or in products fabricated by themanufacturing processes (e.g., in an electrode fabricated using diatomfrustules, devices comprising such an electrode). Reduction inagglomeration of nanostructures may facilitate providing increasedactive surface area for electrolyte to access (e.g., increase activesurface area of an electrode, better electrical performance of a devicecomprising such an electrode). In some embodiments, the porosity ofsurfaces of diatom frustules can facilitate electrolyte access to theactive surface area, such as facilitating diffusion of electrolytic ionsto active surfaces of an electrode (e.g., diatom frustules can have poresizes of about 1 nanometers (nm) to about 500 nm).

In some embodiments, the frustule 50 can be thickly covered by thenanostructures 52. In some embodiments, a ratio of a mass of thenanostructures 52 to a mass of the frustule 50 is between about 1:1 andabout 20:1, between about 5:1 and about 20:1, or between about 1:1 andabout 10:1. The nanostructures 52 preferably have a mass greater than amass of the frustule 50 prior to coating. The mass of the nanostructures52 may be determined by weighing the frustules 50 before and aftercoating with the difference being the mass of the nanostructures 52.

Structures 52 can be formed or deposited onto a surface of a frustule 50at least in part by combining a frustule 50 with a formulationcomprising a desired material to allow coating or seeding of thestructures 52 onto a surface of the frustule 50.

As described herein, structures 52 on a surface of the frustule 50 maycomprise zinc oxide, such as zinc oxide nanowires. In some embodiments,zinc oxide nanowires can be formed on a surface of the frustule 50 bycombining the frustule 50 with a solution comprising zinc acetatedihydrate (Zn(CH₃CO₂)₂. 2H₂O) and ethanol. For example, a solutionhaving a concentration of 0.005 mol/L (M) zinc acetate dihydrate inethanol may be combined with frustules 50 so as to coat a surface of thefrustules 50. The coated frustules 50 may then be air dried and rinsedwith ethanol. In some embodiments, the dried frustules 50 can then beannealed (e.g., at a temperature of about 350° C.). The zinc oxidenanowires may then be allowed to grow on the coated surface of thefrustules 50. In some embodiments, the annealed frustules 50 aremaintained at a temperature above room temperature (e.g., maintained ataround a temperature of about 95° C.) to facilitate formation of thezinc oxide nanowires.

Frustules 50 may also comprise a material formed on or deposited onto asurface of the frustules 50 to modify a characteristic or attribute ofthe frustules 50. For example, an electrically insulating frustule 50may be made electrically conductive by forming or applying anelectrically conductive material on one or more surfaces of the frustule50. A frustule 50 may include a material comprising silver, aluminum,tantalum, brass, copper, lithium, magnesium, combinations thereof,and/or the like. In some embodiments, a frustule 50 includes materialcomprising ZnO. In some embodiments, a frustule 50 includes materialcomprising an oxide of manganese. In some embodiments, a frustule 50includes a material comprising a semiconductor material, includingsilicon, germanium, silicon germanium, gallium arsenide, combinationsthereof, and/or the like. The surface modifying material may be on anexterior surface and/or an interior surface of the frustules 50. In someembodiments, frustules 50 comprise a surface modifying material on allor substantially all of the surfaces of the frustules 50.

A material can be formed or deposited onto a surface of a frustule 50 inpart through combining a frustule 50 with a formulation including adesired material to allow coating or seeding of the material onto asurface of the frustule 50.

As described herein, a material may be deposited onto a surface of thefrustule 50. In some embodiments, the material comprises a conductivemetal such as silver, aluminum, tantalum, copper, lithium, magnesium,and brass. In some embodiments, coating a surface of the frustule 50with a material comprising silver includes, at least in part, combiningthe frustule 50 with a solution comprising ammonia (NH₃) and silvernitrate (AgNO₃). In some embodiments, the solution can be prepared in aprocess similar to a process often used in preparing Tollens' reagent.For example, preparation of the solution may comprise addition ofammonia to aqueous silver nitrate to form a precipitate, followed byfurther addition of ammonia until the precipitate dissolves. Thesolution may then be combined with the frustule 50. As an example, 5milliliters (mL) of ammonia may be added to 150 mL of aqueous silvernitrate while stirring such that a precipitate forms, followed byaddition of another 5 mL of ammonia until the precipitate dissolves. Amixture may then be formed by combining the solution with 0.5 grams (g)of frustules 50 and an aqueous solution of glucose (e.g., 4 g of glucosedissolved in 10 mL of distilled water). The mixture may then be placedinto a container immersed in a bath maintained at a temperature (e.g., awarm water bath maintained at a temperature of about 70° C.) so as tofacilitate the coating of the frustules 50.

Growing Nanostructures on Diatom Frustules or Portions of DiatomFrustules

As described herein, diatomaceous earth is naturally occurring sedimentfrom fossilized microscopic organisms called diatoms. The fossilizedmicroorganisms comprise hard frustules made from highly structuredsilica with sizes often between about 1 micron and about 200 microns.Different species of diatoms have different 3D shapes and features,which vary from source to source.

Diatomaceous earth can include a highly porous, abrasive, and/or heatresistant material. Due to these properties, diatomaceous earth hasfound wide applications including filtering, liquid absorption, thermalisolation, as ceramic additive, mild abrasive, cleaning, food additive,cosmetics, etc.

Diatom frustules have attractive features for nanoscience andnanotechnology—they have naturally occurring nano structures: nanopores,nanocavities and nanobumps (e.g., as shown in FIGS. 1 to 3 ). Theabundance of frustule shapes depending on the diatom species (e.g., morethan 105) is another attractive property. Silicon dioxide, from whichthe diatom frustules are made, can be coated or replaced by a usefulsubstance while preserving the diatom nanostructures. Diatomnanostructures may serve as a useful nanomaterial for many processes anddevices: dye-sensitized solar cells, drug delivery, electroluminescentdisplays, anode for Li-ion batteries, gas sensors, biosensors, etc.Formation of MgO, ZrO₂, TiO₂, BaTiO₃, SiC, SiN, and Si may beaccomplished using high temperature gas displacement of SiO₂.

In some embodiments, diatom frustules can be coated with 3Dnanostructures. The diatoms may be coated on inner and/or outersurfaces, including inside the nanopores of the diatoms. The coatingsmay not preserve the diatom structure precisely. However, coatings maythemselves have nanopores and nanobumps. Such silicafrustules/nanostructures composites use frustules as support. Thenanostructured material may have small nanoparticles densely joinedtogether: nanowires, nanospheres, nanoplates, dense array ofnanoparticles, nanodisks, and/or nanobelts. Overall, the composites mayhave a very high surface area.

Nanostructures comprising various materials may be formed on surfaces offrustules. In some embodiments, nanostructures comprise a metallicmaterial. For example, nanostructures formed on one or more surfaces ofa frustule may comprise zinc (Zn), magnesium (Mg), aluminum (Al),mercury (Hg), cadmium (Cd), lithium (Li), sodium (Na), calcium (Ca),iron (Fe), lead (Pb), nickel (Ni), silver (Ag), combinations thereof,and/or the like. In some embodiments, nanostructures comprise metaloxides. For example, nanostructures formed on a frustule surface maycomprise zinc oxide (ZnO), manganese dioxide (MnO₂), manganese(II, III)oxide (Mn₃O₄), manganese(II) oxide (MnO), manganese(III) oxide (Mn₂O₃),mercury oxide (HgO), cadmium oxide (CdO), silver(I,III) oxide (AgO),silver(I) oxide (Ag₂O), nickel oxide (NiO), lead(II) oxide (PbO),lead(II, IV) oxide (Pb₂O₃), lead dioxide (PbO₂), vanadium(V) oxide(V₂O₅), copper oxide (CuO), molybdenum trioxide (MoO₃), iron(III) oxide(Fe₂O₃), iron(II) oxide (FeO), iron(II, III) oxide (Fe₃O₄), rubidium(IV)oxide (RuO₂), titanium dioxide (TiO₂), iridium(IV) oxide (IrO₂),cobalt(II, III) oxide (Co₃O₄), tin dioxide (SnO₂), combinations thereof,and/or the like. In some embodiments, nanostructures comprise othermetal-containing compounds, including for example, manganese(III)oxohydroxide (MnOOH), nickel oxyhydroxide (NiOOH), silver nickel oxide(AgNiO₂), lead(II) sulfide (PbS), silver lead oxide (Ag₅Pb₂O₆),bismuth(III) oxide (Bi₂O₃), silver bismuth oxide (AgBiO₃), silvervanadium oxide (AgV₂O₅), copper(I) sulfide (CuS), iron disulfide (FeS₂),iron sulfide (FeS), lead(II) iodide (PbI₂), nickel sulfide (Ni₃S₂),silver chloride (AgCl), silver chromium oxide or silver chromate(Ag₂CrO₄), copper(II) oxide phosphate (Cu₄O(PO₄)₂), lithium cobalt oxide(LiCoO₂), metal hydride alloys (e.g., LaCePrNdNiCoMnAl), lithium ironphosphate (LiFePO₄ or LFP), lithium permanganate (LiMn₂O₄), lithiummanganese dioxide (LiMnO₂), Li(NiMnCo)O₂, Li(NiCoAl)O₂, cobaltoxyhydroxide (CoOOH), titanium nitride (TiN), combinations thereof,and/or the like.

In some embodiments, nanostructures formed on surfaces of frustules cancomprise non-metallic or organic material. In some embodiments, thenanostructures can comprise carbon. For example, the nanostructures maycomprise multi-wall and/or single-wall carbon nanotubes, graphene,graphite, carbon nano-onions, combinations thereof, and/or the like. Insome embodiments, nanostructures may comprise fluorocarbons (e.g.,CF_(x)), sulfur (S), conductive n/p-type doped polymers (e.g.,conductive n/p-type doped poly(fluorene)s, polyphenylenes, polypyrenes,polyazulenes, polynaphthalenes, poly(pyrrole)s, polycarbazoles,polyindoles, polyazepines, polyanilines, poly(thiophene)s,poly(3,4-ethylenedioxythiophene), and/or poly(p-phenylene sulfide)),combinations thereof, and/or the like.

Nanostructures formed on a surface of a diatom frustule may include: 1)silver (Ag) nanostructures; 2) zinc-oxide (ZnO) nanostructures; 3)carbon nanotubes “forest;” and/or 4) manganese-containingnanostructures. As described herein, the diatom frustules havingnanostructures formed on one or more of their surfaces can be used forenergy storage devices such as batteries and supercapacitors, solarcells, and/or gas sensors. Nanostructures may be formed on one or moresurfaces of unbroken frustules and/or broken frustules. In someembodiments, frustules or portions of frustules used in thenanostructure formation process may have been extracted through aseparation procedures comprising separation steps described herein(e.g., the separation process 20 shown in FIGS. 4A and 4B). In someembodiments, before the growth of nanostructured active materials,frustules can be pretreated with one or more functionalized chemicals(e.g., siloxanes, fluorosiloxanes, proteins, and/or surfactants). Insome embodiments, before the growth of nanostructured active materials,frustules can be pre-coated with a conductive materials (e.g., metal,and/or a conductive carbon), and/or a semiconductor material. Forexample, frustules may be pre-coated with silver (Ag), gold (Au), copper(Cu), nickel (Ni), platinum (Pt), graphene, graphite, carbon nanotubes,silicon (Si), germanium (Ge)), a semiconductor-containing alloy (e.g.,an aluminum-silicon (AlSi) alloy), combinations thereof, and/or thelike.

In some embodiments, nanostructures are grown using two step approaches.The first step generally includes the growth of seeds on the surface ofdiatom frustules. Seeds are nanostructures that are directly bonded(e.g., chemically bonded) to the surfaces of the diatom frustules, andmay have certain grain size and/or uniformity. Energy may be provided tocreate such bonds. The seeding process may be conducted under hightemperatures and/or involve other techniques that can create heat orsome other form of energy gain.

A second step of forming nanostructures generally includes growing thefinal nanostructures from the seeds. Frustules pre-coated with seeds maybe immersed in environments of initial materials under certainconditions. The nanostructures may include one or more of nanowires,nanoplates, dense nanoparticles, nanobelts, nanodisks, combinationsthereof, and/or the like. The form factor may depend on conditions ofthe growth of the nanostructures (e.g., morphology of the nanostructurescan depend on one or more growth conditions during forming of thenanostructures on the seed layer, including for example a growthtemperature, a pattern of heating, inclusion of a chemical additiveduring the nanostructure growth, and/or combinations thereof).

An Example Process of Forming Ag Nanostructures on Surfaces of DiatomFrustules

The initial coating of silica with silver (or seeding) can be realizedby reduction of a Ag⁺ salt using microwave, ultrasonication, surfacemodification, and/or reduction of silver nitrate (AgNO₃) with a reducingagent.

The seed growth step may include dissolution of a silver salt and areducing agent in a solvent (e.g., the reducing agent and the solventcan be the same substance) and dispersing purified diatoms in themixture. During and/or after the dissolution, a physical force likemixing, stirring, heating, ultrasonication, microwaves, combinationsthereof, and/or the like may be applied. The seed layer growth processmay occur for various amounts of time.

Examples of Growing Ag Seeds on Surfaces of Diatom Frustules

Example 1 includes the following steps: 0.234 g of purified diatoms, 0.1g AgNO₃, and 50 mL of molten at 60° C. PEG 600 (polyethylene glycol) aremixed in a beaker. In some embodiments, a mixture comprising cleandiatoms, a silver contributing component (e.g., silver nitrate), and areducing agent may be heated by a cyclic heating regimen. In someembodiments, the reducing agent and the solvent can be the samesubstance. For example, a mixture may be heated for about 20 minutes toabout 40, alternating the heat from about 100 Watt to about 500 Wattevery minute. For example, the mixture comprising cleaned diatoms,silver nitrate, and molten PEG was heated by microwave for about 30 min.The microwave power was altered from 100 to 500 Watt every minute toprevent overheating the mixture. Some commercial microwaves allow theuser to determine the temperature of the contents after a certainduration, and/or to determine multiple temperatures after variousdurations (e.g., to define a temperature ramp), during which themicrowave controls the power in order to achieve that result. Forexample, the microwave may determine that a lower power is needed toheat 50 mL of water to 85° C. in 2 min than to heat 50 mL of water to85° C. in 1 min, and this adjustment may be made during the heatingprocess, for example based on temperature sensors. For another example,the microwave may determine that a lower power is needed to heat 50 mLof water to 85° C. in 2 min than to heat 100 mL of water to 85° C. in 2min, and this adjustment may be made during the heating process, forexample based on temperature sensors. The diatoms were centrifuged andwashed with ethanol. The seeds are illustrated in FIGS. 5B and 5C.

Example 2 includes the following steps: Mix 45 mL ofN,N-dimethylformamide, 0.194 g of 6,000 MW PVP (polyvinylpyrrolidone), 5mL of 0.8 mM AgNO₃ in water, and 0.1 g of filtered and purified diatomsin a beaker. A tip of an ultrasonic processor (e.g., 13 mm diameter, 20kHz, 500 Watt) is placed in the mixture and the beaker with the mixtureplaced in an ice bath. Tip amplitude is set at 100%. Sonication lasts 30min. The diatoms are cleaned after the procedure in ethanol two timesusing bath sonication and centrifugation at 3,000 RPM for 5 min. Thenthe process is repeated two more times until seeds are seen on thediatoms.

FIG. 5B shows a SEM image, at 50 k× magnification, of silver seeds 62formed on a surface of a diatom frustule 60. FIG. 5C shows a SEM image,at 250 k× magnification, of the silver seeds 62 formed on the surface ofthe diatom frustule 60.

Example of Forming Silver Nanostructures on Silver Seeded DiatomFrustule Surfaces

Further coating of the seeded frustules with silver may be conductedunder argon (Ar) atmosphere to inhibit formation of silver oxides. Insome embodiments, diatom frustule portions can be sintered (e.g., heatedto a temperature of about 400° C. to about 500° C.) to obtain silverfrom silver oxides which may have formed on one or more surfaces ofdiatom frustule portions, including silver oxides formed during theprocess to further coat the seeded diatom frustule portions with silver.For example, sintering of diatom frustule portions may be performed ondiatom frustule portions used in fabricating a conductive silver ink(e.g., a UV-curable conductive silver ink as described herein). In someembodiments, the sintering may be under an atmosphere configured topromote reduction of silver oxides to silver (e.g., hydrogen gas).Sintering the diatom frustule portions that the conductive silver inkcomprises to obtain silver from silver oxides may improve conductivityof the conductive silver ink, for example because silver is moreconductive than silver oxide and/or because silver-silver contact (e.g.,as opposed to silver-silver oxide contact and/or silver oxide-silveroxide contact) may be increased. Other methods of obtaining silver fromsilver oxide may also be suitable in place of or in combination withsintering, including, for example, a process comprising a chemicalreaction.

Formation of nanostructures on the seed layer may include a silver salt,a reducing agent, and a solvent. A mixing step, a heating step, and/or atitration step (e.g., to facilitate interaction of components of thenanostructure growth process) may be applied to form the nanostructureson the seed layer.

An example of process for forming the nanostructures on the seed layer(e.g., forming a thick silver coating) includes the following process:

5 mL of 0.0375 M PVP (6,000 MW) solution in water is placed in onesyringe and 5 mL of 0.094 M AgNO₃ solution in water is placed in anothersyringe. 0.02 g of seeded washed and dried diatoms mixed with 5 mL ofethylene glycol heated to about 140° C. The diatoms are titrated withsilver salt (e.g., AgNO₃) and PVP solutions at a rate of about 0.1milliliter per minute (mL/min) using a syringe pump. After the titrationis finished, the mixture is stirred for about 30 min. Then diatoms arewashed (e.g., washed two times) using ethanol, bath sonication, andcentrifugation.

FIGS. 5D and 5E show SEM images of an example where silvernanostructures 64 have formed on a surface of diatom frustule 60. FIGS.5D and 5E show a frustule 60 having a thick nanostructured coating withhigh surface area. FIG. 5D is a SEM image of the frustule surface at 20k× magnification, while FIG. 5E shows a SEM image of the frustulesurface at 150 k times magnification. FIG. 5L is another SEM image, at50 k× magnification, of the diatom frustule 60 having silvernanostructures 64 on a surface. The thick nanostructured coating ofdiatom frustule 60 can be seen in FIG. 5L.

Examples of suitable reducing agents for Ag growth include commonreducing agents used for silver electroless deposition. Some suitablereducing agents for silver electroless deposition include hydrazine,formaldehyde, glucose, sodium tartrate, oxalic acid, formic acid,ascorbic acid, ethylene glycol, combinations thereof, and/or the like.

Examples of suitable Ag+salts and oxides include silver salts. The mostcommonly used silver salts are soluble in water (e.g., AgNO₃). Suitablesilver salts may include an ammonium solution of AgNO₃(e.g.,Ag(NH₃)₂NO₃). In some embodiments, any silver (I) salt or oxide can beused (e.g., soluble and/or not soluble in water). For example, silveroxide (Ag₂O), silver chloride (AgCl), silver cyanide (AgCN), silvertetrafluoroborate, silver hexafluorophosphate, silver ethylsulphate,combinations thereof, and/or the like, may also be suitable.

Suitable solvents may include: water, alcohols such as methanol,ethanol, N-propanol (including 1-propanol, 2-propanol (isopropanol orIPA), 1-methoxy-2-propanol), butanol (including 1-butanol, 2-butanol(isobutanol)), pentanol (including 1-pentanol, 2-pentanol, 3-pentanol),hexanol (including 1-hexanol, 2-hexanol, 3-hexanol), octanol, N-octanol(including 1-octanol, 2-octanol, 3-octanol), tetrahydrofurfuryl alcohol(THFA), cyclohexanol, cyclopentanol, terpineol; lactones such as butyllactone; ethers such as methyl ethyl ether, diethyl ether, ethyl propylether, and polyethers; ketones, including diketones and cyclic ketones,such as cyclohexanone, cyclopentanone, cycloheptanone, cyclooctanone,acetone, benzophenone, acetylacetone, acetophenone, cyclopropanone,isophorone, methyl ethyl ketone; esters such ethyl acetate, dimethyladipate, propylene glycol monomethyl ether acetate, dimethyl glutarate,dimethyl succinate, glycerin acetate, carboxylates; carbonates such aspropylene carbonate; polyols (or liquid polyols), glycerols and otherpolymeric polyols or glycols such as glycerin, diol, triol, tetraol,pentanol, ethylene glycols, diethylene glycols, polyethylene glycols,propylene glycols, dipropylene glycols, glycol ethers, glycol etheracetates 1,4-butanediol, 1,2-butanediol, 2,3-butanediol,1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,8-octanediol,1,2-propanediol, 1,3-butanediol, 1,2-pentanediol, etohexadiol,p-menthane-3,8-diol, 2-methyl-2,4-pentanediol; tetramethyl urea,n-methylpyrrolidone, acetonitrile, tetrahydrofuran (THF), dimethylformamide (DMF), N-methyl formamide (NMF), dimethyl sulfoxide (DMSO);thionyl chloride; sulfuryl chloride, combinations thereof, and/or thelike.

In some embodiments, a solvent can also act as a reducing agent.

Example Method of Fabricating A Low-Cost UV-Curable Silver-DiatomConductive Ink

Thermally curable silver flake and silver nanoparticle conductive inksare available from a variety of manufacturers such as Henkel Corp.,Spraylat Corp., Conductive Compounds, Inc., DuPont, Inc., CreativeMaterials Corp., et al. A much less common product is a silverconductive ink curable with ultraviolet (UV) light. Only a fewsuppliers, (e.g., Henkel Corp.) have such inks in their productofferings. UV-curable silver conductive inks often can be very costlybecause of the high silver loading, and high cost per square meterrelative to the conductivity. The conductivities can be as much as 5 to10 times lower than thermally cured silver conductive inks applied atthe same wet film thickness.

There is clearly a need for a low-cost UV-curable silver with at leastthe same or better conductivity than the currently available UV-curableinks. Some UV-curable silvers may not take full advantage of the volumeof silver present in the ink, so there is a need to develop a silver inkusing much less silver that has similar or better conductivity and/orcurability than current UV-curable silver inks.

A difficulty with developing UV-curable silvers may be due to the UVabsorption properties of silver. In thermally-cured silver inks, silverflakes having a high aspect ratio may be used to produce the highestconductivity by maximizing the inter-flake contact area. If this type ofsilver flake is mixed with a UV-curable resin system appropriate for aconductive ink, applied to a surface using printing or other coatingprocesses, and then exposed to UV light, most of the UV light may beabsorbed by the silver before the UV light can scatter through the wetlayer of silver ink. UV absorption by silver flakes can impede orprevent UV light-initiated polymerization from occurring in the wet inkfilm (e.g., impeding or preventing UV light-initiated polymerization ofthe wet ink beyond a certain depth). Reduced polymerization of the inkfilm may result in an incompletely cured layer of silver ink that maynot adhere to the substrate, for example due to the bottom-most portionsof the silver ink layer being uncured and wet. Lower aspect-ratio silverparticles may be used in UV-curable silver inks to obtain suitablecuring throughout the applied layer of silver ink by increasing thenumber of possible light scattering paths through the applied layer ofsilver ink. The low aspect-ratio particles have decreased surface area,which may reduce inter-flake contact area, and in turn may reduceconductivity of the cured film relative to what would be possible if ahigh aspect-ratio flake was used. If this curing problem could besolved, larger aspect ratio silver flake with higher conductivity couldbe used in the silver ink, which may improve conductivity of theresulting silver film and/or reduce the amount of silver used to achievea high conductivity.

In some embodiments, a non-conducting substrate (e.g., a diatom frustuleportion, such a diatom frustule flake) can be plated with silver. UVlight may pass through the perforations on one or more surfaces of thebody of the diatom frustule flake. Using the silver plated diatom flakein the silver ink may facilitate curing of the silver ink, enabling theuse of high aspect ratio flakes in the silver ink. In some embodiments,a silver ink comprising silver plated diatom frustules may enableincreased conductivity of the cured silver ink while, at the same time,reducing the cost of the ink.

In some embodiments, the portions of diatom frustules (e.g., brokendiatom frustules) used in the silver ink can be purified and separatedfrom the intact diatom particles, and one or more surfaces of theportions of diatom frustules may be electrolessly coated with silver,for example according to methods described herein.

A diatom surface may be perforated by a regular pattern of holes oropenings (e.g., including holes approximately 300 nm in diameter), evenwhen coated with silver. The openings may be large enough to allow UVwavelengths to scatter through the silver coated diatom particles.Broken diatoms coated with silver may comprise shards in the form ofhigh aspect-ratio perforated flakes. FIG. 5F shows a SEM image of abroken piece of diatom frustule (e.g., a diatom frustule flake 60A)coated with Ag nanostructures (e.g., silver nanostructures 64).

In some embodiments, a silver coated perforated diatom flake can be usedfor making a UV-silver ink which can be cured when a moderately thicklyink is used (e.g., a silver ink having a thickness of about 5 μm toabout 15 μm), even though the conductive particles have highaspect-ratios and therefore large surface areas. Large surface areas ofthe frustule flake may create excellent inter-flake conductivity byincreasing the number of inter-flake electrical contacts, resulting in ahighly conductive ink that uses substantially only as much silver as isneeded to achieve the desired sheet conductivity, with the rest of thevolume taken up by the inexpensive diatom filler material and UV binderresin.

The silver nanostructure may cover substantially all surfaces of thefrustules, including the inner surfaces of the frustule perforations,but without blocking the perforations (e.g., one or more surfaces of theperforations and frustule surfaces may be plated with silvernanostructures and/or a silver seed layer). The perforations in the Agcoated diatom flakes may allow UV radiation to pass through the diatomflakes, facilitating curing to a deep depth within the applied silverink films while allowing current to be conducted directly from one sideof the flake to the other through the perforations. A reduction in thelength of the conduction pathways through the flake may reduce theoverall resistance of the cured film made from the silver ink.

An example UV light-induced polymerizable ink formulation may includecomponents from the following list. In some embodiments, a silver inkhaving diatom frustule flakes can be fabricated by combining componentslisted below, including, for example, combining a plurality of frustuleportions (e.g., frustule flakes) having silver nanostructures formed onone or more surfaces with one or more other silver ink components listedbelow. A silver film may be fabricated by curing the silver ink with aUV light source.

1) Diatoms, any of a variety of species, plated (e.g., havingnanostructure formed thereon) with between about 10 nm and about 500 nmthick Ag coating. A thickness of the Ag coating may depend on a poresize of the diatom perforations. Ratios in the formulation may bebetween about 50% and about 80% by weight. An example diatom specieswhose fragments can be used is Aulacoseira sp. 1.

2) A polar vinyl monomer with good affinity for silver, such asn-vinyl-pyrrolidone or n-vinylcaprolactam.

3) An acrylate oligomer with good elongation properties as a rheologymodifier and to improve flexibility in the cured film.

4) One or more difunctional or trifunctional acrylate monomers oroligomers as crosslinking agents to produce a tougher, more solventresistant cured film through increased cross-linking. These materialsmay be chosen to function as photoinitiation synergists, which mayimprove surface curing. Examples may include ethoxylated or propoxylatedhexandiol acrylates such as Sartomer CD560®, ethoxylatedtrimethylpropane triacrylate available, for example from Sartomer underthe product code SR454®, or triallyl cyanurate available, for examplefrom Sartomer under the product code SR507A®. Acrylated amine synergistsmay be an option, and examples may include Sartomer CN371® and SartomerCN373®.

5) An acrylate-based flow and level agent to reduce bubbling and improvewet ink quality (e.g., suitable flow and level agents may includeModaflow 2100®, Modaflow 9200®). Improved wet ink quality may, in turn,improve cured silver ink film quality.

6) One or more photoinitiators appropriate for pigment loaded inksystems. In some embodiments, at least one of the photoinitatiors issensitive to wavelengths near to or smaller than the silver plateddiatom flake's average pore size so that UV photons may pass through thepore in order to initiate polymerization underneath the flake and/orscatter through a perforation in another silver plated diatom flake topenetrate even deeper into the uncured film to initiate polymerizationthere. Examples of photoinitiators can include Ciba Irgacure 907® andIsopropyl thioxanthoone (ITX, available from Lambson, UK under thetradename Speedcure ITV)).

7) An optional adhesion promoting acrylate (e.g., 2-carboxyethylacrylate).

8) A optional wetting agent to lower surface tension and improve flakewetting (e.g., DuPont Capstone FS-30® and DuPont Capstone FS-31®).

9) An optional UV stabilizer to suppress premature polymerizationtriggered by the presence of silver metal (e.g., hydroquinone and methylethyl hydroquinone (MEHQ)).

10) An optional low boiling point solvent for lowering viscosity tofacilitate the silver ink formulation being used in high speed coatingprocesses, including processes such flexographic printing, gravureprinting, combinations thereof, and/or the like.

In some embodiments, a silver ink comprising diatom frustule portionscan be thermally cured. In some embodiments, the silver ink can beexposed to a heat source. For example, the silver ink may be heated tofacilitate a polymerization reaction between polymer components of thesilver ink. In some embodiments, thermal curing of the silver ink canfacilitate removal of a solvent component. For example, the silver inkcan be exposed to a heat source to raise a temperature of the silver inkabove a boiling point of the silver ink solvent component to facilitateremoval of the solvent component.

Example Processes of Forming Zinc-Oxide (ZnO) Nanostructures on Surfacesof Diatom Frustules

Generally, the ZnO seeds on a substrate can be deposited using spray orspin coating of colloidal ZnO or with thermal decomposition of zincsalts solutions. For example, thermal decomposition of zinc acetateprecursor can give vertically well-aligned ZnO nanowires.

Growth of ZnO nanostructures from seeds may be realized by thehydrolysis of Zn salts in a basic solution. The process can be performedat room temperature or at higher temperatures. Microwave heating cansignificantly accelerate growth of nanostructures. Depending on growthparameters, different nanostructures were observed (e.g., morphology ofthe nanostructures can depend on one or more growth conditions duringforming of the nanostructures on the seed layer, including for example agrowth temperature, a pattern of heating, inclusion of a chemicaladditive during the nanostructure growth, and/or combinations thereof).For example, a chemical additive may be used to achieve a desiredmorphology of nanostructures. ZnO nanostructures also can be doped tocontrol their semiconducting properties.

Example Processes for Growing ZnO Seeds on Surfaces of Diatom Frustules

1. Building seeds of ZnO can be realized by heating a mixture of 0.1 gof purified diatoms and 10 mL of 0.005 M zinc acetate (Zn(CH₃COO)₂)(e.g., a zinc contributing component) in ethanol to about 200° C. (e.g.,including from about 175° C. to about 225° C.) until dry. SEM images,each at 100 k× magnification, of a ZnO seeded frustule surface are shownin FIGS. 5G and 5H. FIGS. 5G and 5H show SEM images of seeds 72comprising ZnO formed on a surface of a frustule 70. FIG. 5G shows a SEMimage, at 100 k× magnification, of a frustule surface having seeds 72comprising zinc-oxide. FIG. 5H shows a SEM image, at 100 k×magnification, of a frustule surface having seeds 72 comprisingzinc-oxide.

In some embodiments, a process of seeding frustule surfaces with ZnOcomprises forming a mixture comprising the following composition: about2 weight % to about 5 weight % frustules, about 0.1 weight % to about0.5 weight % of zinc salt (e.g., Zn(CH₃COO)₂), and about 94.5 weight %to about 97.9 weight % of an alcohol (e.g., ethanol). In someembodiments, forming the ZnO seeds on the frustule surfaces comprisesheating the mixture. The mixture may be heated to a desired temperaturefor a period of time to facilitate formation of ZnO seeds on surfaces ofthe frustules and removal of liquids from the mixture. Heating may beperformed using any number of heating apparatuses capable of heating themixture to the desired temperature for the desired period of time, suchas a hot plate. In some embodiments, the mixture can be heated to atemperature of greater than about 80° C. to facilitate formation of ZnOseeds on the frustule surfaces and to dry the ZnO seeded frustules. Insome embodiments, the heated mixture may be further heated in a vacuumoven to facilitate further removal of liquids. For example, the mixturemay be heated in a vacuum oven at a pressure of about 1 millibar (mbar)and at a temperature of about 50° C. to about 100° C.

In some embodiments, the dried frustules can be subjected to anannealing process. In some embodiments, the annealing process can beconfigured to facilitate desired formation of ZnO, for example byfacilitating decomposition of the zinc salt to form ZnO. In someembodiments, conditions of the annealing process can be configured toachieve further drying of the frustules, such as by evaporation of anyremaining liquids from the frustules. In some embodiments, the annealingprocess can comprise heating the dried frustules in an inert atmosphereat a temperature of about 200° C. to about 500° C. In some embodiments,the annealing process can include heating in an atmosphere comprisingargon gas (Ar) and/or nitrogen gas (N₂).

Example Processes for Growing ZnO Nanostructures on ZnO Seeded Surfacesof Diatom Frustules

2. As described herein, ZnO nanostructures can be grown on the ZnO seedsformed on frustule surfaces. In some embodiments, ZnO nanostructuregrowth can be conducted in mixture of 0.1 g seeded frustules with 10 mLof 0.025 M ZnNO₃ (e.g., a zinc contributing component) and 0.025 Mhexamethylenetetramine solution (e.g., a basic solution) in water. Themixture can be heated to about 90° C. (e.g., including from about 80° C.to about 100° C.) for about two hours (e.g., including from about onehour to about three hours) on a stir plate, or by using a cyclic heatingroutine (e.g., microwave heating) for a duration of about 10 min (e.g.,including for a duration of about 5 minutes to about 30 minutes) wherethe sample is heated by about 500 Watt of power (e.g., including fromabout 480 Watt to about 520 Watt) for about 2 min (e.g., including about30 seconds to about 5 minutes, about 1 minute to about 5 minutes, about5 minutes to about 20 minutes) and then heating can be turned off forabout 1 min (e.g., including from about 30 seconds to about 5 minutes)before repeating the heating at 500 Watt. The resulting nanowires 74 onthe inside and outside surfaces of a frustule 70 using theabove-described process are shown in FIGS. 5I and 5J. FIG. 5I shows aSEM image, at 50 k× magnification, of ZnO nanowires 74 formed on bothinside surfaces and outside surfaces of a diatom frustule 70. In someembodiments, ZnO nanowires 74 can be formed on a portion of a surface onan interior of a diatom frustule 70. For example, ZnO nanowires 74 maybe formed on all or substantially all surfaces on an interior of adiatom frustule 70. ZnO nanowires 74 may be formed on all orsubstantially all interior and exterior surfaces of a diatom frustule70. The drawings of this application provide proof that growth ofnanostructures (e.g., ZnO nanowires) on diatom frustules is possible,including growth of nanostructures (e.g., ZnO nanowires) on the insideof diatom frustules. Coating all or substantially all sides of thediatom frustules with ZnO nanostructures may provide increasedconductivity of a material (e.g., ink or a layer printed therefrom)comprising the ZnO nanostructure-coated diatom frustules (e.g., anincreased bulk conductivity and/or sheet conductivity), for example incomparison to materials (e.g., ink or a layer printed therefrom)comprising ZnO nanostructures formed only on the outside of a substrate.FIG. 5J shows a SEM image, at 25 k× magnification, of ZnO nanowires 74formed on surfaces of a diatom frustule 70. FIGS. 5M and 5N areadditional SEM images of diatom frustule 70 having ZnO nanowires 74 onone or more surfaces. FIG. 5M is a SEM image of diatom frustule 70 at 10k× magnification. FIG. 5N is a SEM image of diatom frustule 70 at 100 k×magnification. The polyhedral, polygonal cross-section, and rod-likestructure of the ZnO nanowires 74 and their attachment to the surface ofthe frustule 70 can be more clearly seen in FIG. 5N. When the heatingwas performed in a microwave at 100 Watt (e.g., including from about 80Watt to about 120 Watt; and at about 2 min on, then about 1 min off, andrepeated for a total duration of about 10 min), nanoplates 76 can beformed on a surface of the frustules 70 (e.g., as shown in FIG. 5K).

In some embodiments, a process for forming ZnO nanostructures on one ormore surfaces of frustules seeded with ZnO comprises forming a mixturecomprising the following composition: about 1 weight % to about 5 weight% seeded frustules, about 6 weight % to about 10 weight % zinc salt(e.g., Zn(NO₃)₂), about 1 weight % to about 2 weight % of a base (e.g.,ammonium hydroxide (NH₄OH)), about 1 weight % to about 5 weight % of anadditive (e.g., hexamethylenetetramine (HMTA)), and about 78 weight % toabout 91 weight % purified water. In some embodiments, forming the ZnOnanostructures comprises heating the mixture. The mixture may be heatedusing microwave. For example, the mixture may be heated in a microwavedevice to a temperature of about 100° C. to about 250° C. for about 30minutes (min) to about 60 min (e.g., in a Monowave 300 for a smallerscale synthesis, such as for a mixture about 10 mL to about 30 mL, or aMasterwave BTR for a larger scale synthesis, such as for about a 1 liter(L) mixture, both commercially available from Anton Paar® GmbH). In someembodiments, the mixture may be stirred while being heated by themicrowave. For example, the mixture may be stirred during heating by amagnetic stirrer at about 200 rotations per minute (RPM) to about 1000RPM. Use of microwave heating may advantageously facilitate reducedduration of heating, providing a more efficient fabrication process.

In some embodiments, a frustule comprising ZnO nanostructures formedthereon comprises about 5 weight % to about 95 weight % of the ZnO,including about 10 weight % to about 95 weight %, about 20 weight % toabout 95 weight %, about 30 weight % to about 95 weight %, about 40weight % to about 95 weight %, or about 50 weight % to about 95 weight%, the remaining mass being the frustule. In some embodiments, afrustule comprising ZnO nanostructures formed thereon comprises about 5weight % to about 95 weight % of the frustule, the remaining mass beingthe ZnO. In some embodiments, a frustule comprising ZnO nanostructuresformed thereon comprises about 40 weight % to about 50 weight % of thefrustule, the remaining mass being the ZnO. In some embodiments, afrustule comprising ZnO nanostructures formed thereon comprises about 50weight % to about 60 weight % of the ZnO, the remaining mass being theZnO. In some embodiments, a mass of the ZnO to a mass of the frustulecan be about 1:20 to about 20:1, including about 1:15 to about 20:1,about 1:10 to about 20:1, about 1:1 to about 20:1, about 2:1 to about10:1, or about 2:1 to about 9:1. The ZnO nanostructures preferably havea mass greater than a mass of the frustules prior to coating. In someembodiments, the mass of the ZnO nanostructures to the mass of thefrustule can be greater than about 1:1, about 10:1, or about 20:1. Incertain such embodiments, an upper limit may be based on, for example,openness of pores of the frustules (e.g., ZnO nanostructures notcompletely occluding the pores).

In some embodiments, a mass of the ZnO to a mass of the frustule can beabout 1:20 to about 100:1, including about 1:1 to about 100:1, about10:1 to about 100:1, about 20:1 to about 100:1, about 40:1 to about100:1, about 60:1 to about 100:1, or about 80:1 to about 100:1. In someembodiments, the mass of the ZnO nanostructures to the mass of thefrustule can be greater than about 30:1, about 40:1, about 50:1, about60:1, about 70:1, about 80:1 or about 90:1. In some embodiments, a massof the ZnO nanostructures to a mass of the frustule can be selected toprovide desired device performance.

In some embodiments, pores of the frustules may be occluded by thenanostructures. For example, ZnO nanostructures may be formed onsurfaces of the frustules, including surfaces within pores of thefrustules, such that the ZnO nanostructures may occlude or substantiallyocclude some or all of the pores of the frustules.

The mass of the ZnO nanostructures may be determined by weighing thefrustules before and after coating with the difference being the mass ofthe ZnO nanostructures. In some embodiments, the composition of themixture for forming ZnO nanostructures can be selected such that ZnOcovered frustules comprising a desired ZnO weight % can be formed. Insome embodiments, the weight % of ZnO on frustule surfaces can beselected based on a desired mass of surface active material on anopposing energy storage device electrode. For example, the compositionof the mixture for forming the ZnO nanostructures can be selected basedon the mass of an oxide of manganese in an opposing energy storageelectrode, such as the mass of one or more of MnO, Mn₂O₃, Mn₃O₄ andMnOOH. For example, based on stoichiometric calculations, a mass ofMn₂O₃ in an energy storage device electrode can be at least about 2.5times that of ZnO in an opposing electrode.

Referring to FIG. 5O, a SEM image at 500× magnification of a pluralityof frustules 70 having ZnO nanostructures formed thereon is shown. Thefrustules 70 covered with ZnO nanostructures were first seeded with ZnOusing a mixture consisting essentially of about 2 weight % to about 5weight % frustules, about 0.1 weight % to about 0.5 weight %Zn(CH₃COO)₂, and about 94.5 weight % to about 97.9 weight % ethanol. Themixture for forming ZnO seeded frustules was heated to a temperaturegreater than about 80° C. for a duration to form the ZnO seededfrustules and achieve desired drying of the ZnO seeded frustules.Subsequently, ZnO nanostructures were formed on the ZnO seeded frustulesusing a mixture consisting essentially of about 1 weight % to about 5weight % ZnO seeded frustules, about 6 weight % to about 10 weight %Zn(NO₃)₂, about 1 weight % to about 2 weight % ammonium hydroxide(NH₄OH), about 1 weight % to about 5 weight % hexamethylenetetramine(HMTA), and about 78 weight % to about 91 weight % purified water. Themixture was heated using microwave to a temperature of about 100° C. toabout 250° C. for about 30 minutes (min) to about 60 min to facilitateformation of the ZnO nanostructures and drying of the frustules. Asshown in FIG. 5O, unexpectedly, the plurality of frustules 70 having ZnOnanostructures formed thereon did not or substantially did notagglomerate. Each frustule 70 was individually covered or substantiallycovered by ZnO nanostructures. Each of the frustules 70 having ZnOnanostructures formed thereon shown in FIG. 5O included about 50% toabout 60% by weight of ZnO. FIG. 5P shows a SEM image at 5 k×magnification of an individual frustule 70 having ZnO nanostructuresformed thereon. The ZnO nanostructures on the frustule 70 of FIG. 5Pwere formed using the process described with reference to FIG. 5O. Asshown in FIG. 5P, the frustule 70 is covered by ZnO nanoflakes 78. Asshown in FIG. 5P, the frustule 70 comprising ZnO nanoflakes 78 formedthereon is porous. For example, the ZnO nanoflakes 78 did not occludepores of the frustules 70, advantageously facilitating transport ofelectrolyte through an electrode comprising the frustules 70 having theZnO nanoflakes 78 formed thereon.

Examples of suitable Zn salts which can be used for both ZnO seeding andnanostructures growth include: zinc acetate hydrate, zinc nitratehexahydrate, zinc chloride, zinc sulfate, sodium zincate, combinationsthereof, and/or the like.

Examples of suitable bases for ZnO nanostructures growth may include:sodium hydroxide, ammonium hydroxide, potassium hydroxide,tetramethylammonium hydroxide, lithium hydroxide,hexamethylenetetramine, ammonia solutions, sodium carbonate,ethylenediamine, combinations thereof, and/or the like.

Examples of suitable solvents for formation of ZnO nanostructuresinclude one or more alcohols. Solvents described herein as beingsuitable for Ag nanostructures growth may also be suitable for ZnOnanostructure formation.

Examples of additives that may be used for nanostructures morphologycontrol may include tributylamine, triethylamine, triethanolamine,diisopropylamine, ammonium phosphate, 1,6-hexadianol,triethyldiethylnol, isopropylamine, cyclohexylamine, n-butylamine,ammonium chloride, hexamethylenetetramine, ethylene glycol,ethanolamine, polyvinylalcohol, polyethylene glycol, sodium dodecylsulphate, cetyltrimethyl ammonium bromide, carbamide, combinationsthereof, and/or the like.

Example Process of Forming Carbon Nanotubes on a Surface of A DiatomFrustule

Carbon nanotubes (e.g., multiwall and/or single-wall) can be grown on adiatom surface (e.g., inside and/or outside) by chemical vapordeposition technique and its varieties. In this technique, the diatomsare firstly coated with catalyst seeds and then a mixture of gases isintroduced. One of the gases may be a reducing gas and another gas maybe a source of carbon. In some embodiments, a mixture of gases may beused. In some embodiments, a neutral gas can be included for theconcentration control (e.g., argon). Argon may also be used to carryliquid carbonaceous material (e.g., ethanol). The seeds for forming acarbon nanotube can be deposited as metals by such techniques as spraycoating and/or introduced from a liquid, a gas, and/or a solid andreduced later under elevated temperatures by pyrolysis. The reduction ofcarbonaceous gases may occur at higher temperatures, for example in arange of about 600° C. to about 1100° C.

Both the seed coating process and gas reactions can be realized onfrustules surfaces due to nanoporosity. Techniques have been developedfor carbon nanotubes “forest” growth on different substrates includingsilicon, alumina, magnesium oxide, quartz, graphite, silicon carbide,zeolite, metals, and silica.

Examples of suitable metal compounds for growth of catalyst seeds caninclude nickel, iron, cobalt, cobalt-molybdenum bimetallic particles,copper (Cu), gold (Au), Ag, platinum (Pt), palladium (Pd), manganese(Mn), aluminum (Al), magnesium (Mg), chromium (Cr), antimony(Sn),aluminum-iron-molybdenum (Al/Fe/Mo), Iron pentacarbonyl (Fe(CO)₅), iron(III) nitrate hexahydrate (Fe(NO₃)₃·6H₂O), iron (III) nitratehexahydrate (CoCl₂·6H₂O) ammonium molybdate tetrahydrate((NH₄)₆Mo₇O₂₄·4H₂O), ammonium molybdate tetrahydrate ((NH₄)₆Mo₇O₂₄·4H₂O)(MoO₂Cl₂) alumina nanopowder, mixtures thereof, and/or the like.

Examples of suitable reducing gases may include ammonia, nitrogen,hydrogen, mixtures thereof, and/or the like.

Examples of suitable gases which may serve as a source of carbon (e.g.,carbonaceous gases) may include acetylene, ethylene, ethanol, methane,carbon oxide, benzene, mixtures thereof, and/or the like.

Example Processes of Forming Manganese-Containing Nanostructures onSurfaces of Diatom Frustules

In some embodiments, manganese-containing nanostructures can be formedon one or more surfaces of a frustule. In some embodiments, an oxide ofmanganese can be formed on one or more surfaces of a frustule. In someembodiments, nanostructures comprising oxide of manganese having theformula Mn_(x)O_(y) where x is about 1 to about 3 and where y is about 1to about 4, can be formed on one or more surfaces of a frustule. Forexample, nanostructures comprising manganese dioxide (MnO₂), manganese(II, III) oxide (Mn₃O₄), manganese (II) oxide (MnO), and/or manganese(III) oxide (Mn₂O₃) can be formed on one or more surfaces of a frustule.In some embodiments, nanostructures comprising manganese oxyhydroxide(MnOOH) can be formed on one or more surfaces of a frustule. In someembodiments, a membrane of an energy storage device can includefrustules having manganese-containing nanostructures. In someembodiments, a printed energy storage device (e.g., a battery, acapacitor, a supercapacitor, and/or a fuel cell) can include one or moreelectrodes having a plurality of frustules which comprisemanganese-containing nanostructures. In some embodiments, an ink usedfor printing a film can comprise a solution in which frustulescomprising manganese-containing nanostructures are dispersed.

In some embodiments, one or more electrodes of a battery can includefrustules comprising manganese-containing nanostructures on one or moresurfaces (e.g., an electrode of a zinc-manganese battery). A chargedbattery can include a first electrode including frustules comprisingnanostructures comprising manganese dioxide (MnO₂) and a secondelectrode comprising zinc (e.g., frustules comprising a zinc coating).In some embodiments, the second electrode can comprise other materials.A discharged battery can include a first electrode including frustulescomprising nanostructures comprising manganese (II, III) oxide (Mn₃O₄),manganese (II) oxide (MnO), manganese (III) oxide (Mn₂O₃), and/ormanganese oxyhydroxide (MnOOH) and a second electrode including zincoxide (ZnO) (e.g., frustules comprising nanostructures comprising zincoxide). In some embodiments, the second electrode of the dischargedbattery can comprise other materials. In some embodiments, a chargedbattery can include a first electrode comprising frustules havingmanganese (II, III) oxide (Mn₃O₄), manganese (II) oxide (MnO), manganese(III) oxide (Mn₂O₃), and/or manganese oxyhydroxide (MnOOH)nanostructures formed thereon and a second opposing electrode comprisingZnO nanostructures formed thereon. In some embodiments, the battery canbe a rechargeable battery.

A method of forming manganese-containing nanostructures on a diatomfrustule portion can include adding the frustules to an oxygenatedmanganese acetate solution, and heating the frustules and the oxygenatedmanganese acetate solution. An example of a process for forming Mn₃₀₄ onone or more surfaces of a frustule is provided. For example, pure water(e.g., pure water commercially available from EMD Millipore Corporation,of Billerica, MA) can be bubbled with oxygen gas (02) for a duration ofabout 10 minutes (min) to about 60 min (e.g., 02 purging) to formoxygenated water. Manganese(II) acetate (Mn(CH₃COO)₂) can then bedissolved in the oxygenated water at a concentration of about 0.05moles/liter (M) to about 1.2 M to form an oxygenated manganese acetatesolution.

Frustules can be added to the oxygenated manganese acetate solution.Frustules added to the oxygenated manganese acetate solution may nothave any previously formed nanostructures and/or coatings on frustulesurfaces. In some embodiments, frustules added to the oxygenatedmanganese acetate solution can have one or more nanostructures and/orcoatings on frustule surfaces. In some embodiments, frustules added tothe oxygenated manganese acetate solution can have one or morenanostructures and/or coatings on at least some portions of the frustulesurfaces. For example, frustules may have carbon-containingnanostructures on portions of frustule surfaces such thatmanganese-containing nanostructures formed according to one or moreprocesses as described herein can be interspersed amongst thecarbon-containing nanostructures. In some embodiments, carbon-containingnanostructures can include reduced graphene oxide, carbon nanotubes(e.g., single wall and/or multi-wall), and/or carbon nano-onions.Carbon-containing nanostructures can be formed on frustule surfacesaccording to one or more processes as described herein or otherprocesses.

In some embodiments, frustules can be added to the oxygenated manganeseacetate solution such that the solution comprises about 0.01 weight % toabout 1 weight % of frustules. In some embodiments, other Mn²⁺ salts canbe suitable. In some embodiments, other oxidizing agents (e.g.,peroxides) can be suitable.

In some embodiments, growth of manganese-containing nanostructures canbe conducted using a thermal technique and/or a microwave technique. Insome embodiments, desired growth of nanostructures can involve a longerduration when using a thermal method. For example, a thermal techniquemay include using thermal heating in the nanostructure growth process.An example of a thermal method of growing nanostructures may includemixing (e.g., by stirring using any number of suitable techniques)frustules in the oxygenated manganese acetate solution for a duration ofabout 15 hours to about 40 hours (e.g., about 24 hours), whilemaintaining the mixture at a temperature of about 50 degrees C. (° C.)to about 90° C. (e.g., at about 60° C.). In some embodiments, thetemperature of the mixture can be maintained by thermally heating themixture.

In some embodiments, a microwave method of growing nanostructures canfacilitate a shorter nanostructure growth process and/or facilitate ascalable nanostructure growth process. For example, a microwave methodof nanostructure growth may include using microwave heating in thenanostructure growth process. An example of a nanostructure growthprocess using the microwave technique may include adding frustules tothe oxygenated manganese acetate solution, and maintaining the mixtureat a temperature of about 50° C. to about 150° C. for about 10 minutes(min) to about 120 min. The mixture may be stirred while it is beingmaintained at the temperature.

In some embodiments, manganese-containing structures having areddish-brown color (e.g., after washing and drying) can form on one ormore surfaces of frustules using one or more processes described herein.In some embodiments, the manganese oxide structures can have atetrahedral shape. A reddish-brown color may indicate presence ofmanganese(II, III) oxide (Mn₃O₄). In some embodiments, formation oftetrahedral nanocrystals can indicate presence of manganese(II, III)oxide (Mn₃O₄).

FIG. 5Q is a scanning electron microscope (SEM) image at 20 k×magnification of an example of a frustule 80 having nanostructurescomprising manganese(II, III) oxide (Mn₃O₄) 82 on or more of itssurfaces, where the nanostructures 82 are formed using a microwavemethod of nanostructure growth. FIG. 5R is a SEM image at 50 k×magnification of the frustule 80 shown in FIG. 5Q. The nanostructures 82comprising manganese(II, III) oxide (Mn₃O₄) shown in FIGS. 5Q and 5R canbe formed by using an oxygenated solution having a concentration ofabout 0.15 M manganese acetate prepared by bubbling oxygen gas (O₂)through pure water for a duration of about 30 min. For example,commercial grade oxygen gas (e.g., purity level of greater than 95%,such as at least about 97% pure, or at least about 99% pure) can beused. For example, oxygen gas having a purity of at least about 97% canbe bubbled through a glass frit into a vial (e.g., a vial having avolume of about 20 milliliter (mL)) containing about 15 mL of pure waterfor a duration of about 30 minutes at room temperature (e.g., at about25° C.). A weight of 0.55 grams (g) of manganese acetate tetrahydrate(e.g., commercially available from Sigma-Aldrich Corp.) can be dissolvedin the oxygenated pure water. A weight of 0.005 grams (g) of diatoms canbe added to the oxygenated manganese-containing solution. Then the vialcontaining the mixture comprising the added frustules can be placed in amicrowave (e.g., Monowave 300 microwave, commercially available fromAnton Paar® GmbH), and the synthesis can be conducted at a desiredtemperature for a desired period of time. The mixture comprising thesolution and frustules can be maintained for about 30 minutes at atemperature of about 60° C., for example under continues stirring (e.g.,with a magnetic stir bar, such as at a rotation speed of about 600 rpm).In some embodiments, the mixture can be subsequently diluted with water,and centrifuged (e.g., at about 5000 rpm for about 5 min) such that thesupernatant can be discarded. In some embodiments, the precipitate canbe diluted with water again, then dispersed (e.g., shaking, and/orvortexing) and again centrifuged such that the supernatant can bediscarded. The precipitate can then be dried at about 70° C. to about80° C. in a vacuum oven.

Referring to FIG. 5R, the nanostructures 82 can have a tetrahedralshape. It was observed that the manganese(II, III) oxide (Mn₃O₄)structures surprisingly grow on the surface of the frustules rather thanforming in the solution separate from frustules.

FIG. 5S is a transmission electron microscope (TEM) image ofnanostructures 82 formed on surfaces of the frustule shown in FIGS. 5Qand 5R. One or more individual atoms of the nanostructures 82 can beseen, and a scale is provided for size comparison. FIG. 5T shows anelectron diffraction image of a manganese(II, III) oxide (Mn₃O₄)particle.

In some embodiments, a shape and/or dimension of nanostructures formedon a frustule surface can depend on a parameter of the nanostructureformation process. For example, morphology of nanostructures can dependon a solution concentration and/or a level of oxygenation of thesolution. FIG. 5U is a SEM image at 10 k× magnification of a frustule 90comprising manganese-containing nanostructures 92 formed on itssurfaces, where the manganese-containing nanostructures 92 were formedusing a solution having a higher oxygen concentration (e.g., oxygenpurging of water for a duration of about 40 minutes) and highermanganese concentration (e.g., a manganese acetate concentration ofabout 1 M), as compared to the process used in the formation ofnanostructures 82 shown in FIGS. 5Q and 5R. For example, thenanostructures 92 can be formed on frustules 90 according to the processas described with reference to formation of nanostructures 82 (e.g., ofFIGS. 5Q and 5R), except with the following differences: oxygen gasbubbling of the pure water can be performed for a duration of about 40minutes, with the addition of about 0.9 grams (g) of manganese acetateto the oxygenated pure water, and about 0.01 grams (g) of diatoms can beadded to the manganese-containing solution, and the mixture comprisingthe diatoms and manganese-containing solution can be microwaved at atemperature of about 150° C.

As shown in FIG. 5U, the nanostructures 92 can have an elongatefiber-like shape. In some embodiments, the nanostructures 92 can have athin elongate shape (e.g., thin whisker-like structure). In someembodiments, formation of fiber-like structures can indicate presence ofmanganese oxyhydroxide (MnOOH).

In some embodiments, forming nanostructures comprising one or moreoxides of manganese having the formula Mn_(x)O_(y) where x is about 1 toabout 3 and where y is about 1 to about 4, on one or more surfaces of afrustule can include combining frustules with a manganese source, suchas a manganese salt (e.g., manganese acetate (Mn(CH₃COO)₂)) and a base(e.g., ammonium hydroxide (NH₄OH)) in oxygenated water. In someembodiments, forming the Mn_(x)O_(y) nanostructures on one or moresurfaces of frustules can include forming a mixture comprising thefollowing composition: about 0.5 weight % to about 2 weight % offrustules, about 7 weight % to about 10 weight % of Mn(CH₃COO)₂, about 5weight % to about 10 weight % of NH₄OH and about 78 weight % to about87.5 weight % of oxygenated purified water. In some embodiments,oxygenated purified water for the mixture can be prepared by bubblingoxygen through the purified water for about 10 minutes to about 30minutes. The mixture may be heated using microwave to facilitateformation of the Mn_(x)O_(y) nanostructures (e.g., in a Monowave 300 fora smaller scale synthesis, such as for a mixture about 10 mL to about 30mL, or a Masterwave BTR for a larger scale synthesis, such as for abouta 1 liter (L) mixture, both commercially available from Anton Paar®GmbH). For example, the mixture may be heated using a microwave to atemperature of about 100° C. to about 250° C. for about 30 minutes toabout 60 minutes. In some embodiments, the mixture can be stirred whilebeing heated, for example by a magnetic stirrer at about 200 rotationsper minute (RPM) to about 1000 RPM.

In some embodiments, a frustule comprising an oxide of manganese (e.g.,an oxide having the formula Mn_(x)O_(y) where x is about 1 to about 3and y is about 1 to about 4) nanostructures formed thereon comprisesabout 5 weight % to about 95 weight % of the oxide of manganese,including about 30 weight % to about 95 weight %, about 40 weight % toabout 95 weight %, about 40 weight % to about 85 weight %, about 50weight % to about 85 weight %, about 55 weight % to about 95 weight %,or about 75 weight % to about 95 weight %, the remaining mass being thefrustule. In some embodiments, a frustule comprising an oxide ofmanganese (e.g., an oxide having the formula Mn_(x)O_(y) where x isabout 1 to about 3 and y is about 1 to about 4) nanostructures formedthereon comprises about 5 weight % to about 50 weight % of the frustule,the remaining mass being the oxide of manganese nanostructures. In someembodiments, a mass of the oxide of manganese nanostructures to a massof the frustule can be about 1:20 to about 20:1, including about 1:15 toabout 20:1, about 1:10 to about 20:1, about 1:1 to about 20:1, about 5:1to about 20:1, about 1:1 to about 10:1, or about 2:1 to about 9:1. Theoxide of manganese nanostructures preferably have a mass greater than amass of the frustules prior to coating. In some embodiments, a ratio ofthe mass of the oxide of manganese nanostructures to the mass of thefrustule can be greater than about 1:1, about 10:1, or about 20:1. Incertain such embodiments, an upper limit may be based on, for example,openness of pores of the frustules (e.g., the oxide of manganesenanostructures not completely occluding the pores).

In some embodiments, pores of the frustules may be occluded by thenanostructures. For example, oxide of manganese nanostructures may beformed on surfaces of the frustules, including surfaces within pores ofthe frustules, such that the oxide of manganese nanostructures mayocclude or substantially occlude some or all of the pores of thefrustules.

In some embodiments, a mass of the oxide of manganese nanostructures toa mass of the frustule can be about 1:20 to about 100:1, including about1:1 to about 100:1, about 10:1 to about 100:1, about 20:1 to about100:1, about 40:1 to about 100:1, about 60:1 to about 100:1, or about80:1 to about 100:1. In some embodiments, the mass of the manganesenanostructures to the mass of the frustule can be greater than about30:1, about 40:1, about 50:1, about 60:1, about 70:1, about 80:1 orabout 90:1. In some embodiments, a mass of the manganese nanostructuresto a mass of the frustule can be selected to provide desired deviceperformance.

The mass of the oxide of manganese nanostructures may be determined byweighing the frustules before and after coating with the differencebeing the mass of the oxide of manganese nanostructures. In someembodiments, the composition of the mixture for forming oxide ofmanganese nanostructures can be selected such that a desired oxide ofmanganese weight % can be formed. In some embodiments, the weight % ofthe oxide of manganese on frustule surfaces can be selected based on adesired mass of surface active material on an opposing energy storagedevice electrode. For example, the composition of the mixture forforming the oxide of manganese nanostructures can be selected based onthe mass of ZnO in an opposing energy storage device electrode. In someembodiment, based on stoichiometric calculations, a mass of Mn₂O₃ in anenergy storage device electrode can be at least about 2.5 times that ofZnO in an opposing electrode.

FIG. 5V is a SEM image at 20 k× magnification of a frustule 94comprising oxides of manganese nanostructures 96 formed thereon. Thenanostructures 96 included a mixture of different oxides of manganese,the oxides having the formula Mn_(x)O_(y) where x is about 1 to about 3and y is about 1 to about 4. As shown in FIG. 5V, the frustule 94 isthickly covered by the oxide of manganese nanostructures 96. FIG. 5W isa SEM image at 50 k× magnification of a cross-sectional view of afrustule 94 comprising oxides of manganese nanostructures 96 (e.g.,oxides having the formula Mn_(x)O_(y) where x is about 1 to about 3 andy is about 1 to about 4) formed thereon. The frustule 94 was cut usingfocused ion beam (FIB) technique and a cross-section view of the cutfrustule 94 is shown in FIG. 5W. As shown in FIG. 5W, the oxides ofmanganese nanostructures 96 can be formed on interior and exteriorsurfaces of the frustule 94, and a volume of the nanostructures 96 canbe greater than a volume of the frustule 94. FIG. 5X is a SEM image at100 k× magnification of a sidewall of a frustule 94 comprising oxides ofmanganese nanostructures 96 (e.g., oxides having the formula Mn_(x)O_(y)where x is about 1 to about 3 and y is about 1 to about 4) formedthereon. As shown in FIG. 5X, a sidewall of the frustule 94 can becovered by the oxides of manganese nanostructures 96 while pores on thesidewall are not occluded. A frustule having oxide of manganesenanostructures formed thereon without or substantially without occludingpores of the frustule can advantageously facilitate transport ofelectrolyte through an electrode comprising the frustule covered by theoxide of manganese nanostructures.

The frustules 94 comprising the oxides of manganese nanostructures 96formed thereon shown in FIGS. 5V through 5X were formed using a mixtureconsisting essentially of about 0.5 weight % to about 2 weight % offrustules, about 7 weight % to about 10 weight % of Mn(CH₃COO)₂, about 5weight % to about 10 weight % of NH₄OH and about 78 weight % to about87.5 weight % of oxygenated purified water. The mixture was heated usingmicrowave to a temperature of about 100° C. to about 250° C. for about30 minutes to about 60 minutes. As shown in FIGS. 5V through 5X, thefrustules 94 were thickly covered by the oxides of manganesenanostructures 96. For example, about 75 weight % to about 95% of oxidesof manganese nanostructure covered frustule was the nanostructures andthe remaining mass was the mass of the frustule.

Combination of Coatings

In some embodiments, a combination of coating can also be possible. Forexample, a surface of a frustule may include both a nickel coating and acoating of carbon nanotubes (e.g., such a frustule can be used forenergy storage devices, including supercapacitors).

FIG. 6 schematically illustrates an example embodiment of an energystorage device 100. FIG. 6 may be a cross-section or elevational view ofthe energy storage device 100. The energy storage device 100 includes afirst electrode 140 and a second electrode 150, for example a cathodeand an anode, respectively or irrespectively. The first and secondelectrodes 140, 150 are separated by a separator 130. The energy storagedevice 100 may optionally include one or more current collectors 110,120 electrically coupled to one or both of the electrodes 140, 150.

In some embodiments, the energy storage device 100 comprises a firstelectrode 140, a second electrode 150, and/or a separator 130, any ofwhich may be a membrane or layer, including a deposited membrane orlayer.

A current collector 110, 120 may include any component that provides apath for electrons to external wiring. For example, a current collector110, 120 may be positioned adjacent to the surface of the first andsecond electrodes 140, 150 to allow energy flow between the electrodes140, 150 to be transferred to an electrical device. In the embodimentshown in FIG. 6 , a first current collector layer 110 and a secondcollector layer 120 are adjacent to the surface of the first electrode140 and to the surface of the second electrode 150, respectively. Thecurrent collectors 110, 120 are adjacent to surfaces opposite tosurfaces of the electrode 140, 150, respectively, that are adjacent tothe separator layer 130.

In some embodiments, the current collector 110, 120 comprises anelectrically conductive foil (e.g., graphite, such as graphite paper,graphene, such as graphene paper, aluminum (Al), copper (Cu), stainlesssteel (SS), carbon foam). In some embodiments, the current collector110, 120 comprises an electrically conductive material deposited on asubstrate. For example, the current collector 110, 120 can comprise anelectrically conductive material printed on a substrate. In someembodiments, a suitable substrate can include polyester, polyimide,polycarbonate, cellulose (e.g., cardboard, paper, including coatedpaper, such as plastic coated paper, and/or fiber paper). In someembodiments, the conductive material can comprise silver (Ag), copper(Cu), carbon (C) (e.g., carbon nanotubes, graphene, and/or graphite),aluminum (Al), nickel (Ni), combinations thereof, and/or the like.Examples of a conductive material comprising nickel suitable for currentcollectors are provided in PCT Patent Application No. PCT/US2013/078059,entitled “NICKEL INKS AND OXIDATION RESISTANT AND CONDUCTIVE COATINGS,”filed Dec. 27, 2013, which is incorporated herein by reference in itsentirety.

In some embodiments, an energy storage device 100 includes at least onelayer or membrane comprising frustules. For example, an energy storagedevice 100 may include a layer or membrane comprising a dispersionincluding frustules. The layer or membrane comprising frustules mayinclude, for example, the first electrode 140, the second electrode 150,the separator 130, the first collector layer 110, the second collectorlayer 120, combinations thereof, and/or the like. In some embodiments,the energy storage device 100 includes frustules having a uniform orsubstantially uniform shape, dimension (e.g., diameter, length),material, porosity, a surface modifying material and/or structure, anyother suitable feature or attribute, combinations thereof, and/or thelike. In embodiments in which a plurality of layers of the energystorage 100 device comprise frustules, the frustules may be the same orsubstantially the same (e.g., having similar dimensions) or may bedifferent (e.g., insulating in the separator 130 and conductively coatedin an electrode 140, 150).

The energy storage device 100 may include one or more layers ormembranes comprising frustules having a length in a range from about 0.5μm to about 50 μm, from about 1 μm to about 50 μm, from about 1 μm toabout 40 μm, from about 1 μm to about 30 μm, from about 1 μm to about 20μm, from about 1 μm to about 10 μm, from about 5 μm to about 50 μm, fromabout 5 μm to about 40 μm, from about 5 μm to about 30 μm, from about 5μm to about 20 μm, and from about 5 μm to about 10 μm. In someembodiments, the cylindrically shaped frustules have a length of no morethan about 50 μm, no more than about 40 μm, no more than about 30 μm, nomore than about 20 μm, no more than about 15 μm, no more than about 10μm, or no more than about 5 μm. Other frustule lengths are alsopossible.

The energy storage device 100 may comprise one or more layers ormembranes comprising frustules having diameters within a range of fromabout 0.5 μm to about 50 μm, from about 1 μm to about 50 μm, from about1 μm to about 40 μm, from about 1 μm to about 30 μm, from about 1 μm toabout 20 μm, from about 1 μm to about 10 μm, from about 5 μm to about 50μm, from about 5 μm to about 40 μm, from about 5 μm to about 30 μm, fromabout 5 μm to about 20 μm, and from about 5 μm to about 10 μm. In someembodiments, the cylindrically shaped frustules have a diameter of nomore than about 50 μm, no more than about 40 μm, no more than about 30μm, no more than about 20 μm, no more than about 15 μm, no more thanabout 10 μm, no more than about 5 μm, no more than about 2 μm, or nomore than about 1 μm. Other frustule diameters are also possible.

The energy storage device 100 may comprise frustules having a uniform orsubstantially uniform within-frustule porosity and/orfrustule-to-frustule porosity and/or frustules having porosity within aparticular range. In some embodiments, the energy storage device 100comprises one or more layers or membranes including frustules havingporosities in a range of from about 10% to about 50%, from about 15% toabout 45%, and from about 20% to about 40%. In some embodiments, poreson frustule surfaces can have a size (e.g., a length, width, diameter,and/or longest dimension) of about 1 nanometer (nm) to about 500 nm. Forexample, pores on a frustule surface can have a size that can facilitatedesired energy storage device performance (e.g., diffusion ofelectrolytic ions of the energy storage device to facilitate a desiredelectrical performance of the device). Other frustule porosities arealso possible.

As described herein, an energy storage device 100 may include one ormore layers or membranes including frustules 50 comprising no orsubstantially no surface modifying material and/or surface modifyingstructures 52 applied or formed on a surface of the frustules 50 and/orfrustules 50 comprising a material and/or structures 52 applied orformed on a surface of the frustules 50 to modify a characteristic orattribute of the frustules 50. For example, the separator 130 maycomprise frustules 50 comprising no or substantially no surfacemodifying material and/or surface modifying structures 52 applied orformed on a surface of the frustules 50, and at least one of theelectrodes 140, 150 may comprise frustules 50 comprising a materialand/or structures 52 applied or formed on a surface of the frustules 50to modify a characteristic or attribute of the frustules 50. For anotherexample, the separator 130 may comprise some frustules 50 comprising noor substantially no surface modifying material and/or surface modifyingstructures 52 applied or formed on a surface of the frustules 50 andsome frustules 50 comprising a material and/or structures 52 applied orformed on a surface of the frustules 50 to modify a characteristic orattribute of the frustules 50.

In some embodiments, the energy storage device 100 comprises frustuleshaving a non-uniform or substantially non-uniform shape, dimension,porosity, surface modifying material and/or structure, another suitableattribute, and/or combinations thereof.

In some embodiments, one or more layers or membranes of the energystorage device 100 may be printed. In some embodiments, one or morelayers or membranes of the energy storage device 100 can be printed froman ink. In some embodiments, the ink can be printed using varioustechniques described herein, including stenciling, screen printing,rotary printing, die coating, rotogravure printing, flexo and padprinting, combinations thereof, and/or the like. In some embodiments, aviscosity of the ink can be adjusted based on the printing techniqueapplied (e.g., a desired viscosity may be achieved by adjusting, forexample, a quantity of the solvent used for the ink).

In some embodiments, current collectors may be printed using aconductive ink. For example, the current collector can comprise anelectrically conductive material printed on a substrate. In someembodiments, a suitable substrate can include polyester, polyimide,polycarbonate, cellulose (e.g., cardboard, paper, including coatedpaper, such as plastic coated paper, and/or fiber paper). In someembodiments, the conductive ink may comprise aluminum, silver, copper,nickel, bismuth, conductive carbon, carbon nanotubes, graphene,graphite, combinations thereof, and/or the like. In some embodiments,the conductive material can comprise silver (Ag), copper (Cu), carbon(C) (e.g., carbon nanotubes, graphene, and/or graphite), aluminum (Al),nickel (Ni), combinations thereof, and/or the like. Examples of aconductive material comprising nickel suitable for current collectorsare provided in PCT Patent Application No. PCT/US2013/078059, entitled“NICKEL INKS AND OXIDATION RESISTANT AND CONDUCTIVE COATINGS,” filedDec. 27, 2013, which is incorporated herein by reference in itsentirety.

In some embodiments, an ink can be prepared using a plurality offrustules. The ink comprising the frustules may be printed to form acomponent of an energy storage device, such as an electrode or aseparator of an energy storage device. In some embodiments, the ink maycomprise frustules comprising nanostructures formed thereon, includingone or more nanostructures described herein. For example, an inkcomprising nanostructure covered frustules may be printed to form anelectrode of the energy storage device 100. In some embodiments, the inkmay comprise frustules having no or substantially no nanostructuresformed thereon. For example, an ink comprising frustules having no orsubstantially no surface modifications may be printed to form theseparator 130 of the energy storage device 100.

FIGS. 7A through 7E are schematic diagrams showing cross-sectional viewsof examples of energy storage devices. In some embodiments, the energystorage devices of FIGS. 7A through 7E are printed energy storagedevices. For example, the energy storage devices of FIGS. 7A through 7Emay include a first current collector 110, a second current collector120, a first electrode 140, a second electrode 150 and a separator 130,which are all printed. For example, one or more layers of the printedenergy storage devices of FIGS. 7A through 7C can be printed on separatesubstrates and the separate substrates can be subsequently assembledtogether to form the energy storage device, while layers of the energystorage devices of FIGS. 7D and 7E can be printed on one substrate.

In some embodiments, FIGS. 7A through 7C are schematic diagrams showingcross-sectional views of examples of partially printed energy storagedevices, while FIGS. 7D and 7E are schematic diagrams showingcross-sectional views of fully printed energy storage devices, duringvarious stages of the respective manufacturing processes. The energystorage devices shown in FIGS. 7A through 7C may include currentcollectors 110, 120, which may be printed (e.g., over separatesubstrates) and/or not printed (e.g., acting as a substrate on whichother layers are printed). FIGS. 7D and 7E show cross-sectional views ofenergy storage devices which include current collectors 110, 120, whichmay be printed (e.g., each over a substrate) or not printed (e.g., thefirst current collector 110 in FIG. 7D acting as a substrate on whichother layers are printed, the first and second current collectors 110,120 acting together as a substrate on which other layers are printed inFIG. 7E).

In some embodiments, the first current collector 110, second currentcollector 120, first electrode 140, second electrode 150, and/orseparator 130 of FIGS. 7A through 7E can have one or more propertiesand/or be fabricated as described herein. For example, the first currentcollector 110, second current collector 120, first electrode 140, secondelectrode 150, and/or separator 130 can be printed using one or moretechniques and/or ink compositions as described herein. For example, oneof the electrodes 140, 150 may comprise frustules includingnanostructures comprising an oxide of manganese (e.g., oxide having theformula Mn_(x)O_(y) where x is about 1 to about 3 and y is about 1 toabout 4) and the other of the electrodes 140, 150 may comprise frustulesincluding nanostructures comprising zinc (e.g., ZnO), one or both ofwhich may be printed from an ink. For another example, the separator 130may comprise frustules comprising no or substantially no surfacemodification, which may be printed from an ink. As described herein,non-printed current collectors may comprise an electrically conductivefoil, such as a foil comprising aluminum, copper, nickel, stainlesssteel, graphite (e.g., graphite paper), graphene (e.g., graphene paper),carbon nanotubes, carbon foam, combinations thereof, and the like. Insome embodiments, the conductive foil can be laminated and have apolymer layer on one of its two opposing surfaces.

In FIG. 7A, an energy storage device 200 includes a first structure 202and a second structure 204. The first structure 202 comprises a firstelectrode 140 over a first current collector 110 and a separator 130over the first electrode 140. The second structure 204 comprises asecond electrode 150 over a second current collector 120. In someembodiments, the first electrode 140 can be printed over the firstcurrent collector 110. For example, the first electrode 140 can beprinted directly on and in contact with the first current collector 110.In some embodiments, the separator 130 can be printed over the firstelectrode 140. For example, the separator 130 may be printed directly onand in contact with the first electrode 140. In some embodiments, theseparator 130 can be printed over the first electrode 140 such that theseparator 130 and the first current collector 110 encapsulate orsubstantially encapsulate the first electrode 140. In some embodiments,the second electrode 150 can be printed over the second currentcollector 120, for example directly on and in contact with the secondcurrent collector 120. In some embodiments, a process for fabricatingthe energy storage device 200 can include assembling together the firststructure 202 and the second structure 204. For example, fabricating theenergy storage device 200 shown in FIG. 7A can include bringing thesecond electrode 150 of the second structure 204 into contact with theseparator 130 of the first structure 202 such that the separator 130 isbetween the first electrode 140 and the second electrode 150.

FIG. 7B shows an energy storage device 210 comprising a first structure212 comprising a first electrode 140 over a first current collector 110and a first portion of a separator 130 over the first electrode 140. Theenergy storage device 210 may comprise a second structure 214 comprisinga second electrode 150 over a second current collector 120, and a secondportion of the separator 130 over the second electrode 150. In someembodiments, the second electrode 150 can be printed over the secondcurrent collector 120. For example, the second electrode 150 can beprinted on and in direct contact with the second current collector 120.In some embodiments, the second portion of the separator 130 can beprinted on and in direct contact with the second electrode 150. Forexample, the second portion of the separator 130 can be printed on andin direct contact with the second electrode 150. In some embodiments,the first electrode 140 can be printed over the first current collector110. For example, the first electrode 140 can be printed on and indirect contact with the first current collector 110. In someembodiments, the first portion of the separator 130 can be printed overthe first electrode 140. For example, the first portion of the separator130 can be printed on and in direct contact with the first electrode140. In some embodiments, the first and second portions of the separator130 can be printed such that the first portion of the separator 130 andthe first current collector 110 encapsulate or substantially encapsulatethe first electrode 140, and/or the second portion of the separator 130and the second current collector 120 encapsulate or substantiallyencapsulate the second electrode 150. In some embodiments, a process forfabricating the energy storage device 210 can include assemblingtogether (e.g., coupling) the first structure 212 and the secondstructure 214 to form the energy storage device 210. Assembling thefirst structure 212 and the second structure 214 may comprise providingthe first and second portions of the separator 130 between the firstelectrode 140 and the second electrode 150. For example, fabricating theenergy storage device 210 shown in FIG. 7B can include bringing thesecond portion of the separator 130 of the second structure 214 intocontact with the first portion of the separator 130 of the firststructure 212 such that the two portions of the separator 130 arebetween the first electrode 140 and the second electrode 150.

As shown in FIG. 7C, in some embodiments, an energy storage device 220may comprise a first structure 222 comprising a first electrode 140 overa first current collector 110, a separator 130 over the first electrode140, and a second electrode 150 over the separator 130. The energystorage device 220 may comprise a second structure 224 comprising asecond current collector 120. In some embodiments, the first electrode140 can be printed over the first current collector 110. For example,the first electrode 140 can be printed on and in direct contact with thefirst current collector 110. In some embodiments, the separator 130 canbe printed over the first electrode 140. For example, the separator 130can be printed on and in direct contact with the first electrode 140. Insome embodiments, the separator 130 can be printed over the firstelectrode 140 such that the separator 130 and the first currentcollector 110 encapsulate or substantially encapsulate the firstelectrode 140. In some embodiments, the second electrode 150 can beprinted over the separator 130. For example, the second electrode 150can be printed on and in direct contact with the separator 130. In someembodiments, assembling the energy storage device 220 includes couplingthe first structure 222 and the second structure 224 to form the energystorage device 220. In some embodiments, coupling the first structure222 and the second structure 224 can include bringing the second currentcollector 120 into contact with the second electrode 150 such that thesecond electrode 150 is between the second current collector 120 and theseparator 130.

As described herein, FIGS. 7D and 7E are schematic diagrams of fullyprinted energy storage devices. FIG. 7D shows an example of a verticallystacked energy storage device 230 comprising printed current collectors110, 120, electrodes 140, 150 and a separator 130. Referring to FIG. 7D,in some embodiments, a first current collector 110 of the energy storagedevice 230 can be printed on a substrate. In some embodiments, a firstelectrode 140 can be printed over the first current collector 110. Forexample, the first electrode 140 can be printed on and in direct contactwith the first current collector 110. In some embodiments, a separator130 can be printed over the first electrode 140. For example, theseparator 130 can be printed on and in direct contact with the firstelectrode 140. In some embodiments, a second electrode 150 can beprinted over the separator 130. For example, the second electrode 150can be printed on and in direct contact with the separator 130. In someembodiments, a second current collector 120 can be subsequently printedover the second electrode 150. For example, the second current collector120 can be printed on and in direct contact with the second electrode150. In some embodiments, the second current collector 120 can beprinted over the second electrode 150 such that the second currentcollector 120 and the separator 130 encapsulate or substantiallyencapsulate the second electrode 150. In some embodiments, the separator130 can be printed over the first electrode 140 such that the separator130 and the first current collector 110 encapsulate or substantiallyencapsulate the first electrode 140.

Referring to FIG. 7E, an energy storage device 240 having laterallyspaced electrodes 140, 150 is shown. The energy storage device 240 caninclude a first current collector 110 laterally spaced from a secondcurrent collector 120, and a first electrode 140 and a second electrode150 over the first current collector 110 and the second currentcollector 120, respectively. A separator 130 can be over the firstelectrode 140 and the second electrode 150. For example, the separator130 can be formed between the first electrode 140 and the secondelectrode 150 such that electrodes 140, 150 are electrically insulatedfrom one another. In some embodiments, the separator 130 facilitateselectrical insulation between the first current collector 110 and thesecond current collector 120. In some embodiments, each of the firstcurrent collector 110, the second current collector 120, the firstelectrode 140, the second electrode 150, and the separator 130 can beprinted. For example, the first current collector 110 and the secondcurrent collector 120 may be printed on a substrate. In someembodiments, the first electrode 140 can be printed on and in directcontact with the first current collector 110. For example, the firstelectrode 140 can be printed on and in direct contact with the firstcurrent collector 110. In some embodiments, the second electrode 150 canbe printed over the second current collector 120. For example, thesecond electrode 150 can be printed on and in direct contact with thesecond current collector 120. In some embodiments, the separator 130 canbe printed over the first electrode 140 and the second electrode 150,such as on and in direct contact with both the first electrode 140 andthe second electrode 150. In some embodiments, the separator 130 can beprinted over the first electrode 140 and the second electrode 150 suchthat the separator 130 and the first current collector 110 and thesecond current collector 120 can encapsulate or substantiallyencapsulate the first electrode 140 and the second electrode 150,respectively. In some embodiments, first and second structures eachsimilar to the first structure 202 and the second structure 204 of FIG.7A (e.g., comprising a current collector and an electrode, andoptionally a separator) may be formed with different surface activematerials (e.g., one or more oxides of manganese and ZnO) and thenlaterally coupled.

FIG. 8 shows an example embodiment of a separator layer or membrane 300that may form part of an energy storage device (e.g., the separator 130in any of the energy storage devices described with reference to FIGS. 6and 7A through 7E). The separator 300 includes frustules 320. In someembodiments, an energy storage device includes a separator layer ormembrane 300 comprising frustules 320. For example, an energy storagedevice may include a separator 300 comprising a dispersion includingfrustules 320. As described herein, the frustules 320 may be sortedaccording to a shape, dimensions, material, porosity, combinationsthereof, and/or the like, such that the separator 300 comprisesfrustules 320 having a uniform or substantially uniform shape, dimension(e.g., length, diameter), porosity, material, combinations thereof,and/or the like. For example, the separator 300 may include frustules320 having a cylindrical or substantially cylindrical shape (e.g., asshown in FIG. 8 ), a spherical or substantially spherical shape, anothershape, and/or combinations thereof. In some embodiments, the separator300 includes frustules 320 having a material and/or structures appliedor formed on a surface of the frustules 320. The separator 300 maycomprise frustules 320 comprising no or substantially no surfacemodifying material and/or surface modifying structures applied or formedon a surface of the frustules 320 (e.g., as illustrated in FIG. 8 ). Theseparator 300 may comprise frustules 320 comprising a material and/orstructures applied or formed on a surface of the frustules 320 to modifya characteristic or attribute of the frustules 320. The separator 300may comprise some frustules 320 comprising no or substantially nosurface modifying material and/or surface modifying structures appliedor formed on a surface of the frustules 320 and some frustules 320comprising a material and/or structures applied or formed on a surfaceof the frustules 320 to modify a characteristic or attribute of thefrustules 320.

The separator 300 may comprise frustules 320 having a mechanicalstrength sufficient to enable a stable or substantially stableseparation between a first electrode 140 and a second electrode 150 ofan energy storage device (e.g., any of the first electrode 140 andsecond electrode 150 of FIGS. 6 and 7A through 7E). In some embodiments,the separator 300 comprises frustules 320 configured to increaseefficiency of an energy storage device, for example by enabling areduced separation distance between a first electrode 140 and a secondelectrode 150 and/or by facilitating flow of ionic species between afirst electrode 140 and a second electrode 150. For example, frustules320 may have a uniform or substantially uniform shape, dimension,porosity, surface modifying material and/or structures, combinationsthereof, and/or the like, for improved energy storage device efficiencyand/or mechanical strength. The separator 300 of an energy storagedevice may comprise cylindrical or substantially cylindrical frustules320 including walls having a desired porosity, dimensions, and/orsurface modifying material and/or structures.

The separator 300 may comprise one or more layers of frustules 320. Theseparator 300 comprising frustules 320 may have a uniform orsubstantially uniform thickness. In some embodiments, thickness of aseparator 300 comprising frustules 320 is as thin as possible. In someembodiments, thickness of a separator 300 comprising frustules 320 isfrom about 1 μm to about 100 μm, including from about 1 μm to about 80μm, from about 1 μm to about 60 μm, from about 1 μm to about 40 μm, fromabout 1 μm to about 20 μm, from about 1 μm to about 10 μm, from about 5μm to about 60 μm, from about 5 μm to about 40 μm, from about 5 μm toabout 20 μm, from about 5 μm to about 15 μm, from about 5 μm to about 10μm, from about 10 μm to about 60 μm, from about 10 μm to about 40 μm,from about 10 μm to about 20 μm, from about 10 μm to about 15 μm, andfrom about 15 μm to about 30 μm. In some embodiments, a separatorcomprises a thickness of less than about 100 μm, less than about 90 μm,less than about 80 μm, less than about 70 μm, less than about 60 μm,less than about 50 μm, less than about 40 μm, less than about 30 μm,less than about 20 μm, less than about 15 μm, less than about 10 μm,less than about 5 μm, less than about or 2 μm, less than about or 1 μm,and including ranges bordering and including the foregoing values. Otherthicknesses of the separator 300 are also possible. For example, theseparator 300 may comprise a single layer of frustules 320 such that thethickness of the separator 300 may depend at least in part on adimension of the frustules 320 (e.g., a longest axis, a length, or adiameter).

The separator 300 may comprise frustules 320 having a non-uniform orsubstantially non-uniform shape, dimension, porosity, surface modifyingmaterial and/or structure, combinations thereof, and/or the like.

In some embodiments, the separator 300 can include hollow and/or solidmicrospheres made from non-electrically conducting materials. Forexample, the separator 300 can include hollow and/or solid microspheresmade of glass, alumina, silica, polystyrene, melamine, combinationsthereof, and/or the like. In some embodiments, the microspheres can havesize to facilitate printing of the separator 300. For example, theseparator 300 can include microspheres having a diameter of about 0.1microns (μm) to about 50 μm. Examples of separators comprising hollowand/or solid microspheres are provided in U.S. patent application Ser.No. 13/223,279, entitled, “PRINTABLE IONIC GEL SEPARATION LAYER FORENERGY STORAGE DEVICES,” filed Aug. 9, 2012, which is incorporatedherein by reference in its entirety.

In some embodiments, the separator 300 comprises a material configuredto reduce electrical resistance between a first electrode 140 and asecond electrode 150 of an energy storage device. For example, referringagain to FIG. 8 , in some embodiments, the separator 300 comprises anelectrolyte 340. The electrolyte 340 may include any material thatfacilitates the conductivity of ionic species, including, for example, amaterial comprising mobile ionic species that can travel between a firstelectrode 140 and a second electrode 150 of an energy storage device.The electrolyte 340 may comprise any compound that may form ionicspecies, including but not limited to sodium sulfate (Na₂SO₄), lithiumchloride (LiCl), and/or potassium sulfate (K₂SO₄). In some embodiments,the electrolyte 340 comprises an acid, a base, or a salt. In someembodiments, the electrolyte 340 comprises a strong acid, including butnot limited to sulfuric acid (H₂SO₄) and/or phosphoric acid (H₃PO₄), ora strong base, including but not limited to sodium hydroxide (NaOH)and/or potassium hydroxide (KOH). In some embodiments, the electrolyte340 comprises a solvent having one or more dissolved ionic species. Forexample, the electrolyte 340 may comprise an organic solvent. In someembodiments, the electrolyte 340 includes an ionic liquid or an organicliquid salt. The electrolyte 340 may comprise an aqueous solution havingan ionic liquid. The electrolyte 340 may comprise a salt solution havingan ionic liquid. In some embodiments, the electrolyte 340 comprising anionic liquid includes propylene glycol and/or acetonitrile. In someembodiments, the electrolyte 340 comprising an ionic liquid includes anacid or base. For example, the electrolyte 340 may comprise an ionicliquid combined with potassium hydroxide (e.g., addition of a 0.1 Msolution of KOH).

In some embodiments, the electrolyte 340 can include one or more ionicliquids and/or one or more salts described in U.S. patent applicationSer. No. 14/249,316, entitled “PRINTED ENERGY STORAGE DEVICE,” filedApr. 9, 2014, which is incorporated herein by reference in its entirety.

In some embodiments, the separator 300 comprises a polymer 360, such asa polymeric gel. The polymer 360 may be combined with an electrolyte340. A suitable polymer 360 may exhibit electrical and electrochemicalstability, for example maintaining integrity and/or functionality whencombined with an electrolyte 340, during electrochemical reactions,and/or subjected to an electric potential (e.g., an electric potentialexisting between the electrodes 140, 150 of the energy storage device).In some embodiments, the polymer 360 can be an inorganic polymer. Insome embodiments, the polymer 360 can be a synthetic polymer. Theseparator 300 may include a polymer 360 comprising, for example,cellulose (e.g., cellophane), polyamide (e.g., nylon), polypropylene,polyolefin, polyethylene (e.g., radiation-grafted polyethylene),poly(vinylidene fluoride), poly(ethylene oxide), poly(acrylonitrile),poly(vinyl alcohol), poly(methyl methacrylate), poly(vinyl chloride),poly[bis(methoxy ethoxy ethoxyphosphazene)], poly(vinyl sulfone),poly(vinyl pyrrolidone), poly(propylene oxide), copolymers thereof,combinations thereof, and/or the like. In some embodiments, the polymer360 comprises polytetrafluoroethylene (PTFE), including for example anaqueous solution comprising a dispersion of PTFE in water (e.g., aTeflon® aqueous suspension). In some embodiments, the separator 300 cancomprise asbestos, potassium titanate fibers, fibrous sausage casing,borosilicate glass, zirconium oxide, combinations thereof, and/or thelike. In some embodiments, the electrolyte 340 is immobilized within oron the polymer 360 to form a solid or semi-solid substance. In some suchembodiments, the electrolyte 340 is immobilized on or within a polymericgel, for example to form an electrolytic gel.

In some embodiments, the separator 300 optionally comprises an adhesivematerial to enable improved adherence of frustules 320 within theseparator 300 and/or between the separator 300 and a first electrode 140and/or a second electrode 150 of an energy storage device. In someembodiments, the adhesive material comprises a polymer 360. For example,the adhesive material may comprise a polymer 360 that exhibitselectrical and electrochemical stability, and provides sufficientadhesion within the separator 300 and/or between the separator 300 and afirst electrode 140 and/or a second electrode 150 of an energy storagedevice.

In some embodiments, an ink for printing a separator of an energystorage device comprises a plurality of frustules having no orsubstantially no surface modifications, polymer, ionic liquid,electrolyte salt, and/or a solvent. Examples of suitable solvents areprovided in U.S. patent application Ser. No. 14/249,316, entitled“PRINTED ENERGY STORAGE DEVICE,” filed Apr. 9, 2014, which isincorporated herein by reference in its entirety. In some embodiments, asolvent for an ink used to print a separator can comprise dimethylformamide (DMF), dimethyl acetamide (DMAC), tetramethyl urea, dimethylsulfoxide (DMSO), triethyl phosphate, n-methyl-2-pyrrolidone (NMP),combinations thereof, and/or the like. In some embodiments, the ink forprinting the separator comprises the following composition: about 5weight % to about 20 weight % frustules having no surface modifications(e.g., purified frustules), about 3 weight % to about 10 weight % of thepolymer component (e.g., polyvinylidene fluoride, for example Kynar® ADXcommercially available from Arkema Inc. of King of Prussia, Pa.), about15 weight % to about 40% ionic liquid (e.g., 1-ethyl-3-ethylimidazoliumtetrafluoroborate), about 1 weight % to about 5% salt (e.g., zinctetrafluoroborate), about 25 weight % to about 76 weight % solvent(e.g., N-Methyl-2-pyrrolidone). In some embodiments, other polymers,ionic liquids, salts (e.g., other zinc salt) and/or solvents may also besuitable.

In some embodiments, a process for preparing the ink for a separator caninclude dissolving the binder in the solvent. For example, dissolvingthe binder in the solvent may include heating the mixture comprising thebinder and the solvent for about 5 min to about 30 min at a temperatureof about 80° C. to about 180° C. In some embodiments, the heating can beperformed using a hot plate. In some embodiments, the ionic liquid andelectrolyte salt can be added to the mixture, such as while the mixtureis warm after being heated. The binder, solvent ionic liquid andelectrolyte salt may be stirred to facilitate desired mixing, such asfor about 5 min to about 10 min. In some embodiments, the frustules canbe subsequently added. Addition of the frustules may be facilitated bymixing, such as by using a planetary centrifugal mixer. Mixing may beperformed using the planetary centrifugal mixer for about 1 min to about15 min.

FIG. 9 shows an example electrode layer or membrane 400 that may formpart of an energy storage device (e.g., any of the energy storagedevices as described with reference to FIGS. 6 and 7A through 7E). Theelectrode 400 includes frustules 420. In some embodiments, an energystorage device includes one or more electrode layers or membranes 400comprising frustules 420 (e.g., the first electrode 140 and/or thesecond electrode 150 of any of the energy storage devices as describedwith reference to FIGS. 6 and 7A through 7E). For example, an energystorage device may include an electrode layer or membrane 400 comprisinga dispersion including frustules 420. As described herein, the frustules420 may be sorted according to a shape, dimensions, material, porosity,combinations thereof, and/or the like, such that the electrode 400comprises frustules 420 having a uniform or substantially uniform shape,dimension (e.g., length, diameter), porosity, material, combinationsthereof, and/or the like. For example, the electrode 400 may includefrustules 420 having a cylindrical or substantially cylindrical shape(e.g., as shown in FIG. 9 ), a spherical or substantially sphericalshape, another shape, and/or combinations thereof. In some embodiments,the electrode 400 includes frustules 420 having a material and/orstructures applied or formed on a surface of the frustules 420. Theelectrode 400 may comprise frustules 420 comprising no or substantiallyno surface modifying material, and may be insulating, and/or may havesurface modifying structures applied or formed on a surface of thefrustules 420. The electrode 400 may comprise frustules 420 comprising amaterial and/or structures applied or formed on a surface of thefrustules 420 to modify a characteristic or attribute of the frustules420 (e.g., as schematically illustrated in FIG. 9 by the chickenfoot-shaped features on the surfaces of the frustules 420). Theelectrode 400 may comprise some frustules 420 comprising no orsubstantially no surface modifying material and/or surface modifyingstructures applied or formed on a surface of the frustules 420 and somefrustules 420 comprising a material and/or structures applied or formedon a surface of the frustules 420 to modify a characteristic orattribute of the frustules 420.

The electrode 400 may comprise frustules 420 selected for mechanicalstrength such that an energy storage device including the electrode 400may withstand compressive force and/or shape modifying deformation. Insome embodiments, the electrode 400 comprises frustules 420 configuredto increase efficiency of an energy storage device, for example byfacilitating flow of ionic species within the electrode 400 and/orbetween the electrode 400 and other parts of the energy storage device.For example, frustules 420 may have a uniform or substantially uniformshape, dimension, porosity, surface modifying material and/orstructures, combinations thereof, and/or the like, for improved energystorage device efficiency and/or mechanical strength. The electrode 400of an energy storage device may comprise cylindrical or substantiallycylindrical frustules 420 including walls having a desired porosity,dimensions, and/or surface modifying material and/or structures.

The electrode 400 may comprise one or more layers of frustules 420. Theelectrode 400 comprising frustules 420 may have a uniform orsubstantially uniform thickness. In some embodiments, thickness of anelectrode 400 comprising frustules 420 depends at least in part onresistance, amount of available material, desired energy devicethickness, or the like. In some embodiments, thickness of an electrode400 comprising frustules 420 is from about 1 μm to about 100 μm,including from about 1 μm to about 80 μm, from about 1 μm to about 60μm, from about 1 μm to about 40 μm, from about 1 μm to about 20 μm, fromabout 1 μm to about 10 μm, from about 5 μm to about 100 μm, includingfrom about 5 μm to about 80 μm, from about 5 μm to about 60 μm, fromabout 5 μm to about 40 μm, from about 5 μm to about 20 μm, from about 5μm to about 10 μm, from about 10 μm to about 60 μm, from about 10 μm toabout 40 μm, from about 10 μm to about 20 μm, from about 10 μm to about15 μm, and from about 15 μm to about 30 μm. In some embodiments,thickness of an electrode 400 comprising frustules 420 is less thanabout 100 μm, less than about 90 μm, less than about 80 μm, less thanabout 70 μm, less than about 60 μm, less than about 50 μm, less thanabout 40 μm, less than about 30 μm, less than about 20 μm, less thanabout 10 μm, less than about 5 μm, less than about 2 μm, or less thanabout 1 μm, and including ranges bordering and including the foregoingvalues. Other thicknesses of the separator 300 are also possible.

The electrode 400 may comprise frustules 420 having a non-uniform orsubstantially non-uniform shape, dimension, porosity, surface modifyingmaterial and/or structure, combinations thereof, and/or the like.

In some embodiments, the electrode 400 optionally comprises a materialto enhance the conductivity of electrons within the electrode 400. Forexample, referring again to FIG. 9 , in some embodiments, the electrode400 comprises electrically conductive filler 460 to improve electricalconductivity within the electrode 400. Electrically conductive filler460 may comprise a conductive carbon material. For example, electricallyconductive filler 460 may comprise graphitic carbon, graphene, carbonnanotubes (e.g., single-wall and/or multi-wall), combinations thereof,and/or the like. In some embodiments, electrically conductive filler 460can include a metallic material (e.g., silver (Ag), gold (Au), copper(Cu), nickel (Ni), and/or platinum (Pt)). In some embodiments,electrically conductive filler 460 can include a semiconductor material(e.g., silicon (Si), germanium (Ge)), and/or a semiconductor-containingalloy (e.g., an aluminum-silicon (AlSi) alloy). In energy storagedevices 100 comprising a plurality of electrodes 400, the electrodes 400may include different frustules and/or different additives, for exampleincluding different ions and/or ion-producing species. In someembodiments, the electrode 400 may comprise an electrolyte, for examplethe electrolyte 340 described herein with respect to the separator 300of FIG. 8 . In some embodiments, the electrode 400 may comprise apolymer, for example the polymer 360 described herein with respect tothe separator 300 of FIG. 8 . In some embodiments, the electrode 400 caninclude one or more active materials (e.g., free active materials, suchas active materials in addition to nanostructured active materials onone or more surfaces of diatom frustules).

In some embodiments, the electrode 400 can include a binder. The bindermay comprise a polymer. Suitable polymers, polymeric precursors and/orpolymerizable precursors, for an electrode binder, can include forexample, polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA),polyvinylidene fluoride, polyvinylidene fluoride-trifluoroethylene,polytetrafluoroethylene, polydimethylsiloxane, polyethylene,polypropylene, polyethylene oxide, polypropylene oxide, polyethyleneglycolhexafluoropropylene, polyethylene terephthalatpolyacrylonitrile,polyvinyl butyral, polyvinylcaprolactam, polyvinyl chloride; polyimidepolymers and copolymers (e.g., aliphatic, aromatic and/or semi-aromaticpolyimides), polyamides, polyacrylamide, acrylate and (meth)acrylatepolymers and copolymers such as polymethylmethacrylate,polyacrylonitrile, acrylonitrile butadiene styrene, allylmethacrylate,polystyrene, polybutadiene, polybutylene terephthalate, polycarbonate,polychloroprene, polyethersulfone, nylon, styrene-acrylonitrile resin;polyethylene glycols, clays such as hectorite clays, garamite clays,organomodified clays; saccharides and polysaccharides such as guar gum,xanthan gum, starch, butyl rubber, agarose, pectin; celluloses andmodified celluloses such as hydroxyl methylcellulose, methylcellulose,ethyl cellulose, propyl methylcellulose, methoxy cellulose, methoxymethylcellulose, methoxy propyl methylcellulose, hydroxy propylmethylcellulose, carboxy methylcellulose, hydroxy ethylcellulose, ethylhydroxyl ethylcellulose, cellulose ether, cellulose ethyl ether,chitosan, their copolymers, combinations thereof, and/or the like.

In some embodiments, the electrode 400 can include a corrosion inhibitorand/or one or more other functional additives. In some embodiments, acorrosion inhibitor can include one or more surface active organiccompounds. In some embodiments, a corrosion inhibitor can compriseglycols, silicates, mercury (Hg), cadmium (Cd), lead (Pb), gallium (Ga),indium (In), antimony (Sn), bismuth (Bi), combinations thereof, and/orthe like.

In some embodiments, the electrode 400 optionally comprises an adhesivematerial to enable improved adhesion of frustules 420 within theelectrode 400 and/or between the electrode 400 and another component ofthe energy storage device such as a separator 130 and/or a currentcollector 110, 120. In some embodiments, the adhesive material in theelectrode 400 comprises a polymer, for example the polymer 360 describedherein.

In some embodiments, an ink for printing an electrode of an energystorage device can comprise a plurality of frustules comprisingnanostructures formed on one or more surfaces, a conductive filler(e.g., carbon nanotubes, graphite), a binder component, electrolyte(e.g., ionic liquid, electrolyte salt), and/or a solvent. For example,the electrolyte may have a composition as described herein. In someembodiments, one or more solvents described with reference to aseparator ink may also be suitable for the ink for printing theelectrode. In some embodiments, a solvent for an ink used to print anelectrode can comprise dimethyl formamide (DMF), dimethyl acetamide(DMAC), tetramethyl urea, dimethyl sulfoxide (DMSO), triethyl phosphate,n-methyl-2-pyrrolidone (NMP), combinations thereof, and/or the like. Insome embodiments, the ink for printing the electrode can comprisefrustules having an oxide of manganese nanostructures formed on one ormore surfaces. In some embodiments, the ink for printing the electrodecomprises frustules having ZnO nanostructures formed on one or moresurfaces.

In some embodiments, ink for printing an electrode of an energy storagecomprising an oxide of manganese can have the following composition:about 10 weight % to about 20 weight % frustules having one or moresurfaces covered by the oxide of manganese, about 0.2 weight % to about2 weight % carbon nanotubes (e.g., multi-wall carbon nanotubes, forexample commercially available from SouthWest NanoTechnologies ofNorman, Okla.), up to about 10 weight % graphite (e.g., C65 commerciallyavailable from Timcal Graphite and Carbon, of Switzerland), about 1weight % to about 5 weight % binder (e.g., polyvinylidene fluoride, suchas HSV 900 Kynar® commercially available from Arkema Inc. of King ofPrussia, Pa.), about 2 weight % to about 15 weight % ionic liquid (e.g.,1-ethyl-3-ethylimidazolium tetrafluoroborate), and about 48 weight % toabout 86.8 weight % solvent (e.g., N-Methyl-2-pyrrolidone). In someembodiments, the oxide of manganese has the formula Mn_(x)O_(y) where xis about 1 to about 3 and y is about 1 to about 4. For example, the inkmay be printed to form a cathode of a battery.

In some embodiments, ink for printing an electrode of an energy storagecomprising ZnO can have the following composition: about 10 weight % toabout 20 weight % frustules comprising ZnO nanostructures formedthereon, about 0.2 weight % to about 2 weight % carbon nanotubes (e.g.,multi-wall carbon nanotubes, for example commercially available fromSouthWest NanoTechnologies of Norman, Okla.), up to about 10 weight %graphite (e.g., C65 commercially available from Timcal Graphite andCarbon of Switzerland), about 1 weight % to about 5 weight % binder(e.g., polyvinylidene fluoride, such as HSV 900 Kynar® commerciallyavailable from Arkema Inc. of King of Prussia, Pa.), about 2 weight % toabout 15 weight % ionic liquid (e.g., 1-ethyl-3-ethylimidazoliumtetrafluoroborate), about 0.3 weight % to about 1% weight % electrolytesalt (e.g., zinc tetrafluoroborate), and about 47 weight % to about 86.5weight % solvent (e.g., N-Methyl-2-pyrrolidone). For example, the inkmay be printed to form an anode of a battery.

In some embodiments, the carbon nanotubes can comprise multi-wall and/orsingle wall carbon nanotubes. In some embodiments, other types ofgraphite, polymer binder, ionic liquid and/or solvent can also besuitable.

In some embodiments, a process for preparing the ink for printing theelectrode can be configured to provide desired dispersion of carbonnanotubes in the ink, saturate the frustules with the ionic liquid(e.g., providing ionic liquid within, on interior surfaces, exteriorsurfaces, and/or within pores, of frustules) and/or thoroughly mixcomponents of the ink. In some embodiments, a process of preparing theink comprises dispersing the carbon nanotubes in the ionic liquid. Insome embodiments, the carbon nanotubes can be dispersed in the ionicliquid using an automated mortar and pestle. In some embodiments, thecarbon nanotubes and the ionic liquid may then be dispersed in thesolvent. The carbon nanotubes and ionic liquid may be dispersed in thesolvent using an ultrasonic tip. In some embodiments, the frustulescomprising nanostructures formed thereon (e.g., oxide of manganese orZnO nanostructures) and graphite may be added to the carbon nanotubes,ionic liquid, and solvent, and stirred using a centrifugal mixer. Insome embodiments, the electrolyte salt can also be added to the carbonnanotubes, ionic liquid, and solvent, along with the frustules andgraphite, and stirred using a centrifugal mixer. For example, thefrustules, graphite, carbon nanotubes, ionic liquid, solvent, and/orelectrolyte salt, may be mixed using a planetary centrifugal mixer forabout 1 minutes (min) to about 10 min. In some embodiments, a solutioncomprising the polymer binder in the solvent can be added to the mixturecomprising the frustules, graphite, carbon nanotubes, ionic liquid,solvent, and/or electrolyte salt, and heated. The solution comprisingthe polymer binder and the solvent can have about 10 weight % to about20 weight % of the polymer binder. The mixture comprising the polymerbinder, frustules, graphite, carbon nanotubes, ionic liquid, solvent,and/or electrolyte salt, can be heated to a temperature of about 80° C.to about 180° C. In some embodiments, the heating can be performed forabout 10 min to about 30 min. In some embodiments, a hot plate can beused for heating. In some embodiments, stirring can be performed whileheating (e.g., with a mixing rod).

FIGS. 10 through 13 show electrical performances of examples of printedbatteries comprising oxides of manganese (e.g., oxides having theformula Mn_(x)O_(y) where x is about 1 to about 3 and y is about 1 toabout 4) cathode and a ZnO anode fabricated using processes describedherein. FIG. 10 is a discharge curve graph for a printed Mn_(x)O_(y) andZnO battery, where the cathode included a plurality of frustulescomprising oxides of manganese nanostructures formed thereon and theanode included a plurality of frustules comprising ZnO nanostructuresformed thereon. The battery potential expressed in Volts (V) on they-axis and the duration of discharge expressed in hours (hrs) on thex-axis. The battery was a screen printed 1.27 centimeter (cm) by 1.27 cmsquare (i.e. 0.5 inch (in) by 0.5 inch square). The battery includedprinted current collectors, anode, cathode, and separator. The anode andcathode each had an average thickness of about 40 microns (μm). Thecathode had a total weight of about 0.023 grams (g), and a weight of theoxides of manganese was about 0.01 g. The weight of active material,ZnO, in the anode was in excess.

In FIG. 10 , the battery was discharged from a fully or substantiallyfully charged state to the cut-off voltage of about 0.8 V. The batterywas discharged at about 0.01 amperes/gram (A/g). The batterydemonstrated a capacity of about 1.28 milli-ampere hour (mAh), and acapacity of about 128 milli-ampere hour/gram (mAh/g), based on theweight of the cathode active material. FIG. 11 shows the capacitanceperformance of the printed battery of FIG. 10 after a numbercharge-discharge cycles. The battery was cycled 40 times and thecapacitance performance of each cycle is shown on the y-axis as a % ofthe initial capacitance. As shown in FIG. 11 , the capacitanceperformance can be improved after a number of charge-discharge cycles.

FIG. 12 is a charge-discharge curve of another example of a printedMn_(x)O_(y) and ZnO battery, showing the potential performance of eachcharge-discharge cycle as a function of time during threecharge-discharge cycles. The potential is shown on the y-axis in Volts(V), and time is expressed on the x-axis in hours (hrs). The printedbattery was a screen printed 1.27 centimeter (cm) by 1.27 cm square(i.e. 0.5 inch (in) by 0.5 inch square). The cathode of the batteryincluded a plurality of frustules comprising oxides of manganesenanostructures formed thereon and the anode included a plurality offrustules comprising ZnO nanostructures formed thereon. The batteryincluded printed current collectors, anode, cathode, and separator. Theanode and cathode each had an average thickness of about 40 microns(μm). The cathode had a total weight of about 0.021 grams (g), and theweight of the oxides of manganese was about 0.01 g. The weight of activematerial (e.g., ZnO) in the anode was in excess. The printed battery ofFIG. 12 was charged and discharged at about 0.01 amperes/gram (A/g),based on the weight of active material in the cathode. FIG. 13 is acharge-discharge curve of the printed Mn_(x)O_(y) and ZnO battery ofFIG. 12 , where the charge and discharge was performed at about 0.04A/g. Both sets of curves show good repeatability for both charge anddischarge, indicative that the printed Mn_(x)O_(y)/ZnO battery can be aneffective rechargeable battery.

Supercapacitors Comprising Surface-Modified Diatoms

In the above, energy storage devices that derive various advantagesarising from diatomaceous frustules have been described. In thefollowing, one particular type of such energy storage devices, referredto herein and in the relevant industry as supercapacitors, are describedin detail. Supercapacitors, sometimes also referred to asultracapacitors, electric double layer capacitors (EDLC) orelectrochemical capacitors, are relatively new energy storage deviceswhose characteristics are advantageously similar to traditionalelectrostatic capacitors in some aspects while being similar totraditional batteries, e.g., secondary batteries, in some other aspects.

Similar to certain batteries, supercapacitors have a cathode or apositive electrode and an anode or a negative electrode that areseparated by a porous separator and an electrolyte. For example, theseparator may comprise a dielectric material permeable to ions andsoaked in the electrolyte. Ion transport which occurs from one electrodeto the other as part of an electrochemical reaction during charge ordischarge of a battery does not occur in supercapacitors.

While supercapacitors are similar to traditional electrostaticcapacitors in some aspects, e.g., relatively fast charging capability,they have much higher capacitance compared to traditional electrostaticcapacitors. Unlike traditional electrostatic capacitors that storeenergy in electrodes separated by a dielectric, supercapacitors storeenergy at one or both of interfaces between a cathode and an electrolyteand an anode and the electrolyte.

Capacitance values of supercapacitors may be much higher thantraditional electrostatic capacitors. Some supercapacitors have lowervoltage limits compared to traditional electrostatic capacitors. Forexample, some supercapacitors are operationally limited to about 2.5-2.8V. Some supercapacitors may operate at voltages of 2.8 V and higher.Certain such supercapacitors may exhibit a reduced service life.

Supercapacitors generally have much higher power density than batteriesbecause they can transport charge much faster than batteries.Supercapacitors generally have much lower internal resistance comparedto batteries and, as a result, they do not generate as much heat duringquick charge/discharge. Some supercapacitors can be charged anddischarged millions of times, while many secondary batteries can havesignificantly shorter typical life cycle of 500-10000 times. Somesupercapacitors have significantly lower energy density compared tobatteries. Some commercial supercapacitors are more expensive (highercost per Watt) than commercial batteries.

Because of these and other characteristics, supercapacitors are used inapplications in which many rapid charge/discharge cycles may be neededrather than long term energy storage. For example, applications oflarger units of supercapacitors include cars, buses, trains, cranes andelevators, to name a few, where they are used for regenerative braking,short-term energy storage or burst-mode power delivery. Applications ofsmaller units of supercapacitors include memory backup for staticrandom-access memory (SRAM). Other current or future applications ofsupercapacitors include various consumer electronics, including mobilephones, laptops, electric cars and various other devices in whichbatteries are used. Because they can be recharged much faster comparedto batteries, they are especially attractive for devices that canbenefit from faster charge rates, e.g., minutes instead of hours thatcurrent electric vehicles or mobile phones may spend charging.

In some devices, supercapacitors are used in conjunction with batteriesto take advantage of advantageous characteristics of both. In theseapplications, supercapacitors are used when a quick charge is needed tofill a short-term power need, whereas batteries are used to providelong-term energy. Combining the two into a hybrid energy storage devicecan satisfy both needs while reducing battery stress, which may in turnenable a longer service life of the battery and the supercapacitor.

Because the capacitance of supercapacitors is directly proportional tothe effective surface area of the electrodes, it is desirable for theelectrodes of supercapacitors to have relatively large effective surfaceareas. The relatively large effective surface area can be realized byutilizing electrode materials having high surface to volume ratios. Asdescribed above, because of their nanoporous structure, frustules canadvantageously provide a very large effective surface area to serve as asubstrate on which a surface active material of supercapacitors areformed. As described herein in the context of supercapacitors, a surfaceactive material refers to a portion of the electrode that forms aninterface with an electrolyte to substantially give rise to capacitancecaused by at least one of supercapacitance mechanisms, e.g., electricdouble layer capacitance and/or pseudo capacitance, as described belowin more detail. Nanostructures, e.g., nanoparticles or nanotubes, canadditionally or alternatively provide very large surface areas for agiven volume of the surface active material compared to, e.g., a thinfilm formed of the same material. As described herein in the context ofsupercapacitors, a nanostructure refers to a solid material having atleast one axial dimension that is submicron, e.g., about smaller thanabout 1000 nm, 500 nm, 200 nm, 100 nm or a dimension that is within arange defined by any of these values.

A nanostructure can have any shape described above, e.g., a nanowire, ananosheet, a nanotube, a nanoplate, a nanoparticle, a nanobelt, ananodisk and a rosette shaped nanostructure. The nanostructure can alsohave any three dimensional geometrical shapes, e.g., a sphere, acylinder, a cone, a spheroid, an ellipsoid, a tetrahedron, a pyramid, aprism, a cube, a cuboid, a plate, a disc and a rod to name a few. Insome implementations, the nanostructure can be selected to have aparticular shape based on the crystal structure of the nanostructure. Asdescribed above, the inventors have discovered inventive methods ofmodifying the surfaces of frustules with various surface activematerials. The inventors have recognized that, by synergizing the veryhigh effective surface area of the frustules and the very highsurface-to-volume ratio of nanostructured surface active materials,supercapacitors having higher power and energy densities than existingsupercapacitors can be realized. For example, by modifying surfaces offrustules with nanostructured surface active material having a largesurface to volume ratio, the inventors have realized supercapacitorsthat benefit from the synergistic effect of the frustules and thenanostructured surface active material.

According to various embodiments, a supercapacitor comprises a pair ofelectrodes contacting an electrolyte. In some embodiments, theelectrodes may be interposed by the electrolyte and may further comprisea separator, e.g., immersed in the electrolyte. In various embodiments,one or both of the electrodes comprise a plurality of frustules andsurface active materials. The surface active materials contact theelectrolyte to give rise to one or more supercapacitance mechanismsdescribed below. In some embodiments, each of the frustules has formedthereon the surface active materials. The surface active materials maybe nanostructured to take advantage of the high surface area of thefrustules and/or to take advantage of the high surface to volume ratioof the surface active material, thereby giving rise to improvedsupercapacitance performance, including higher power and/or energydensity. For example, the surface active materials may be in the form ofa plurality of nanostructures covering surfaces of the frustules. Thenanostructures can include one or more of zinc oxide nanostructures,manganese oxide nanostructures or carbon nanostructures. The performanceof the disclosed supercapacitors benefits from the synergistic effect ofthe high surface area provided by the nanoporosity of the structure ofdiatom frustules and the high surface to volume ratio of the surfaceactive materials. Because the surface active materials, e.g.,nanostructures, are grown on diatom frustules, they are notagglomerated, and relatively larger portions of their surface area areaccessible to electrolyte. Because the diatoms frustules are nanoporous,the electrolyte has direct access to the nanostructures and can easilymove throughout the device. The disclosed supercapacitors canadvantageously be manufactured using scalable techniques such asprinting. Manufactured supercapacitors can be used as small scaledevices, for example in printed electronics, and/or can be produced inlarge volume and folded in a shape for more powerful applications.

Without being bound to any theory, supercapacitors can store energy bydifferent mechanisms, which include electric double-layer capacitanceand/or pseudocapacitance. Double layer capacitance has electrostaticcharacteristics, while pseudocapacitance has electrochemicalcharacteristics. The different mechanisms are described in more detailbelow. Depending on whether the storage mechanism has double-layercapacitance characteristics and/or pseudocapacitance characteristics,and depending on whether the supercapacitor has two same or symmetricelectrodes or two different or asymmetric electrodes, the supercapacitorcomprising one or both of the electrodes having a plurality of frustulescoated with nanostructured surface active material can be configured asone of three distinct groups of supercapacitors.

A first group of supercapacitors has both electrodes configured aspseudo capacitors, where each of the electrodes comprises frustules anda transition metal oxide (e.g., manganese oxide or zinc oxide) and isconfigured to give rise to pseudo capacitance. For example, thefrustules may have a transition metal oxide formed thereon in the formof nanostructures. A second group of supercapacitors has both electrodesconfigured as EDLCs, where each of the electrodes comprises frustulesand carbon (e.g., carbon nanotubes) and is configured to give rise todouble layer capacitance. For example, the frustules may have carbonformed thereon in the form of nanostructures. A third group ofsupercapacitors, which may be referred to as hybrid supercapacitors, hasone of the electrodes that is configured as a EDLC and the other of theelectrodes that is configured a pseudo capacitor. When included as partof a hybrid capacitor, the electrode configured as the pseudo capacitormay serve as a cathode or a positively charged electrode, and theelectrode configured as the EDLC may serve as an anode or a negativelycharged electrode. Without being bound to any theory, operationalprinciples of the three groups of supercapacitors are described herein.

FIG. 14A illustrates a cross-sectional view of a supercapacitor 1400having both electrodes configured as a double-layer capacitor. FIG. 14Billustrates a cross-sectional view of the supercapacitor of FIG. 14A inoperation, where a voltage is applied across the electrodes. FIGS. 14Aand 14B illustrate the supercapacitor 1400 in a discharged state and acharged state, respectively. The supercapacitor 1400 includes a firstelectrode 1440, which may be positively charged in operation, and asecond electrode 1450, which may be negatively charged in operation. Thesupercapacitor 1400 optionally includes first and second currentcollectors 1410, 1420 electrically coupled to the electrodes 1440, 1450,respectively. The first and second electrodes 1440, 1450 are interposedby a separator 1430 and are ionically connected to each other via anelectrolyte 1460 filling the gap between the first and second electrodes1440, 1450. The electrolyte 1460 comprises a mixture of positive andnegative ions 1470, 1480 dissolved in a solvent. The surface of each ofthe two electrodes 1440, 1450 contacts the electrolyte 1460 to formactive interfaces. At the active interfaces between the electrodes 1440,1450, and the electrolyte 1460, the double layer capacitance effectarises.

Referring to FIG. 14A, in the discharged state, the positive ions 1470and negative ions 1480 may be dispersed randomly. In operation,referring to FIG. 14B, applying a voltage across the first and secondelectrodes 1440, 1450, e.g., by negatively charging the second currentcollector 1420 relative to the first current collector 1410 and/orpositively charging the first current collector 1410 relative to thesecond current collector 1420, causes both electrodes 1440, 1450 togenerate electrical double layers. Each of the electrical double layersincludes two layers of charge, as illustrated in FIG. 14B. Without beingbound to any theory, for example, a layer of electrostatic charge, e.g.,a sheet of negative electronic charge, may form at the surface of thesecond electrode 1450, e.g., at the surface of the surface activematerial, and an opposite layer of electrostatic charge, e.g., a sheetof positive ionic charge, may form adjacent to the surface of theelectrode 1450 in the electrolyte 1460. The two sheets of charge areseparated by a layer 1490, e.g., a monolayer, of molecules of thesolvent of the electrolyte 1460, sometimes referred to as innerHelmholtz plane (IHP). This layer 1490 of solvent molecules serves as alayer of dielectric giving rise to a first capacitance (C_(d1)) at thesecond electrode 1450 side. In an analogous manner, a layer 1500 ofsolvent molecules forms between a layer of electrostatic charge, e.g., apositive electronic charge layer at the surface of the first electrode1440, e.g., at the surface of the surface active material, and anopposite layer of electrostatic charge, e.g., a negative ionic charge,may form adjacent to the surface of the first electrode 1440 in theelectrolyte 1460. The layer 1500 of solvent molecules serves as anotherlayer of dielectric giving rise to a second capacitance (C_(d2)) at theside of the first electrode 1440.

As described herein, each of the layers 1490, 1500 of solvent moleculesformed adjacent to the first and second electrodes 1450, 1440,respectively, serves as a dielectric layer giving rise to thecapacitances C_(d1) and C_(d2). The capacitors formed at the secondelectrode 1450 and the first electrode 1440 are electrically connectedin series by the electrolyte 1460 to provide a series supercapacitanceCs that can be expressed as:

$\begin{matrix}{\frac{1}{C_{s}} = {\frac{1}{C_{d1}} + \frac{1}{C_{d2}}}} & {{Eq}.\mspace{14mu} 1}\end{matrix}$

For a given solvent of the electrolyte 1460, the amount of charge storedper unit voltage in an EDLC is a function of the electrode size. Similarto classical electrostatic capacitance, the capacitance of Cal arisingfrom the first double layer capacitor on the side of the secondelectrode 1450 may be approximated byC_(d1)=ε₁d₁,  Eq. 2where ε₁ is the permittivity of the solvent of the electrolyte 1460, andd₁ is the effective thickness of the layer 1490 of solvent moleculesformed adjacent to the second electrode 1450. Similarly, the capacitanceC_(d2) arising from the second double layer on the side of the firstelectrode 1440 may be approximated byC_(d2)=ε₂d₂,  Eq. 3where ε₂ is the permittivity and d₂ is the effective thickness of thelayer 1500 of solvent molecules of the electrolyte 1460 formed adjacentto the second electrode 1440. The stored energy in each of thedouble-layers is approximately linear with respect to the capacitance,and corresponds to the concentration of the adsorbed ions. The energy Estored in the supercapacitor can be expressed as:

$\begin{matrix}{{E = \frac{C_{s}AV^{2}}{2}},} & {{Eq}.\mspace{14mu} 4}\end{matrix}$where C_(s) is the supercapacitor capacitance described above, A is theeffective surface area of the electrodes, and V is the voltage. Thepower of the supercapacitor can be expressed as:

$\begin{matrix}{{P_{\max} = \frac{V^{2}}{4R}},} & {{Eq}.\mspace{14mu} 5}\end{matrix}$where R is the equivalent series resistance of the supercapacitor.According to the above expressions of the capacitance, energy and power,the higher power and energy of the supercapacitors are achieved by, fora given electrolyte, increasing the surface area (A) of electrodes 1450,1440, increasing the voltage (V) the supercapacitor and by decreasingthe equivalent resistance (R) attributable to the electrodes,electrolytes and interfaces between the electrode materials andsupercapacitor layers. The electric double-layer capacitance values areextremely high relative to traditional electrostatic capacitors withsimilar macroscopic electrode sizes, arising in part from the extremelythin layers 1490, 1500 of solvent molecules, which can be as thin as amonolayer thickness, e.g., on the order of a few ångströms (0.3-0.8 nm),which can of the order of the Debye length. The active area of theelectrodes are also extremely high as described above, arising from thelarge surface area of the frustules, whose effective surface area isfurther enhanced by the nanostructured active material formed thereon.

Based on the above-described mechanism of EDLC, unlike energy storage inbatteries, the process of generating electric double layer capacitancedoes not involve a transfer of charge between the electrodes usingelectrolyte. While charge in conventional capacitors is transferred viaelectrons, capacitance in double-layer capacitors is related to themoving speed of ions through the electrolyte and through the resistiveporous structure of the frustules. Since no chemical changes take placewithin the electrode or electrolyte, the EDLC can have much highercycling lifetimes compared to batteries.

FIG. 15 illustrates a cross-sectional view of a supercapacitor 1500comprising an electrode that is configured as a pseudo capacitor. Thesupercapacitor 1500 may be configured in a similar manner to thesupercapacitor 1400 illustrated above, except for the structure and thecomposition of the electrodes. While the supercapacitor 1500 includes afirst electrode (not shown), which may be positively charged inoperation, and a second electrode 1550, which may be negatively chargedin operation, only the second electrode 1550 illustrated as a pseudocapacitor is shown for illustration purposes. The first electrode may beconfigured as another pseudo capacitor, or as an EDLC described above.The surface of each of the first electrode and the second electrode 1550contacts the electrolyte 1460. At the contacting interface between thefirst electrode and the second electrode 1550 and the electrolyte 1460,a pseudo capacitance effect arises.

Without being bound to any theory, in operation, applying a voltageacross the first electrode and the second electrode 1550 moves positiveand negative ions in the electrolyte 1460 in opposite directions towardsthe first electrode and the second electrode 1550, where electric doublelayer capacitors may be formed, for example in a similar manner asdescribed above with respect to FIGS. 14A, 14B. Pseudocapacitance canarise when ions in the electrolyte pervade the electric double-layer andbecome adsorbed on the electrode surface, as illustrated in FIG. 15 .This pseudocapacitance stores electrical energy by means of reversibleFaradaic redox reactions on the surface the electrode of asupercapacitor forming an electric double layer described above. Unlikethe electric double layer capacitance effect, the pseudocapacitance isaccompanied with an electron charge-transfer between the electrolyte1460 and the adsorbed ions. This Faradaic charge transfer originates bya very fast sequence of reversible redox, intercalation orelectrosorption processes. The ability of electrodes to exhibitpseudocapacitance depends on the chemical affinity of electrodematerials to the ions adsorbed on the electrode surface as well as onthe structure and the structure of the electrode. Materials exhibitingredox behavior for use as electrodes in pseudo capacitors includetransition-metal oxides. The pseudo capacitance can be expressed as theamount of charge (q) stored per applied potential (V), orC=dq/dV.  Eq. 6

Similar to double layer capacitance, pseudo capacitance orelectrochemical capacitance arises at the surface of the electrode,e.g., at the surface of surface active materials formed on thefrustules. As a result, the specific surface area is directlyproportional to the number of active sites for the redox reactions, andhence the magnitude of pseudocapacitance. This Faradaic energy storagewith fast redox reactions makes charging and discharging much fasterthan batteries.

Faradaic pseudo capacitance arises in conjunction with staticdouble-layer capacitance. Depending on the circumstance, its magnitudemay exceed the value of double-layer capacitance for the same surfacearea by orders of magnitude, depending on the nature and the structureof the electrode.

In the following, various aspects of the supercapacitor are disclosed.While it may not be described in detail, the frustules according tovarious embodiments may have any structure and may be prepared using anymethod described throughout the application, including withoutlimitation, FIGS. 1-5X and the associated text. Various nanostructuresincluding zinc oxide, manganese oxide and carbon nanostructuresaccording to various embodiments may have any structure including, e.g.,FIG. 5 and may be prepared using any method described throughout theapplication, including without limitation, FIGS. 1-5X and the associatedtext.

Supercapacitor Electrodes Comprising Frustules Having Formed ThereonActive Materials

As described above, the interface between the surface active material ofthe electrode and the electrolyte provide sites for energy storage. Inthe following, various surface active materials configured to give riseto pseudo capacitance are described. As described, the surface activematerial can form a coating on the frustules, e.g., on the surfaces ofthe frustules. The coating may be in the form of nanostructured surfaceactive material, which may be formed as part of one or more electrodesof the supercapacitor according to any relevant method, for exampledescribed elsewhere herein.

According to some embodiments, the nanostructured surface activematerial formed on frustule surfaces comprises one or more metal oxides,including, for example, zinc oxide (ZnO), manganese dioxide (MnO₂),manganese(II, III) oxide (Mn₃O₄), manganese(II) oxide (MnO),manganese(III) oxide (Mn₂O₃), mercury oxide (HgO), cadmium oxide (CdO),silver(I,III) oxide (AgO), silver(I) oxide (Ag₂O), nickel oxide (NiO),lead(II) oxide (PbO), lead(II, IV) oxide (Pb₂O₃), lead dioxide (PbO₂),vanadium(V) oxide (V₂O₅), copper oxide (CuO), molybdenum trioxide(MoO₃), iron(III) oxide (Fe₂O₃), iron(II) oxide (FeO), iron(II, III)oxide (Fe₃O₄), rubidium(IV) oxide (RuO₂), titanium dioxide (TiO₂),iridium(IV) oxide (IrO₂), cobalt(II, III) oxide (Co₃O₄), tin dioxide(SnO₂), niobium oxide (Nb₂O₅), combinations thereof, and the like.

According to some embodiments, the nanostructured surface activematerial formed on frustule surfaces comprises one or moremetal-containing compounds, including, for example, manganese(III)oxohydroxide (MnOOH), nickel oxyhydroxide (NiOOH), silver nickel oxide(AgNiO₂), lead(II) sulfide (PbS), silver lead oxide (Ag₅Pb₂O₆),bismuth(III) oxide (Bi₂O₃), silver bismuth oxide (AgBiO₃), silvervanadium oxide (AgV₂O₅), copper(I) sulfide (CuS), iron disulfide (FeS₂),iron sulfide (FeS), lead(II) iodide (PbI₂), nickel sulfide (Ni₃S₂),silver chloride (AgCl), silver chromium oxide or silver chromate(Ag₂CrO₄), copper(II) oxide phosphate (Cu₄O(PO₄)₂), lithium cobalt oxide(LiCoO₂), metal hydride alloys (e.g., LaCePrNdNiCoMnAl), lithium ironphosphate (LiFePO₄ or LFP), lithium permanganate (LiMn₂O₄), lithiummanganese dioxide (LiMnO₂), Li(NiMnCo)O₂, Li(NiCoAl)O₂, cobaltoxyhydroxide (CoOOH), titanium nitride (TiN), combinations thereof, andthe like.

According to some embodiments, the nanostructured surface activematerial formed on frustule surfaces comprises mixed transition metalspinels and binary metal oxides, including, for example, MnFe₂O₄,NiCo₂O₄, CuCo₂O₄, ZnCo₂O₄, Zn₂SNO₄, NiMoO₄, combinations thereof, andthe like.

According to some embodiments, the nanostructured surface activematerial formed on frustule surfaces comprises metal hydroxides,including, for example, Ni(OH)₂, Co(OH)₂, H₂Ti₃O₇, combinations thereof,and the like.

According to other embodiments, the nanostructured surface activematerial formed on frustule surfaces comprises a mixture of any of theabove materials. By way of example, combinations of material that cancoat the frustules include, for example, Mn_(x)O_(y)-Co_(x)O_(y),MnO₂-NiO/Ni(OH)₂, Mn_(x)O_(y)-TiO₂ and Mn_(x)O_(y)-ZnO, to name a few.

In addition to the surface active material that forms the interface withthe electrolyte to provide sites for energy storage, the electrode ofsupercapacitors also includes electrically conducting materials. Inaddition to providing electrical conductivity to the frustules, whichmay be electrically insulating, to enable the electric double layercapacitance or the pseudo capacitance described above, the electricallyconducting material may lower the internal resistance, for higher power,as described above. One or more of the above compounds can be coated onthe frustules with one or more electrically conducting materials. Theelectrically conducting material may be carbon-based in someimplementations. For example, the electrically conducting material maycomprise one or more of various carbon compounds, e.g., graphene,graphite, carbon nanotubes (CNTs), fullerenes, carbon nanofibers and/orcarbon aerogels, to name a few.

The electrically conducting material may be metal-based in someimplementations. For example, the electrically conducting material maycomprise a metallic element or compound, e.g., Ag, Au, stainless steel,Mn, Cu, Ni and/or Al to name a few. In some implementations, theelectrically conducting material may comprise a conducting polymer,e.g., polyaniline (PANI), poly(3,4-ethylenedioxythiophene) (PEDOT),polypyrrole and/or related polymers, to name a few.

While various embodiments are described in which the surface activematerial and the electrically conducting material may be formed onsurfaces of each of the frustules, not all embodiments necessarilyinclude such features. In some embodiments, herein and throughout theentire application, the surface active material and the electricallyconducting material may be formed, in addition to or in lieu of beingformed on the surfaces of each of the frustules, on or over a layer offrustules or between the frustules within a layer of frustules.

While various embodiments are described in which the active material isnanostructured, not all embodiments necessarily include such features.In some embodiments, herein and throughout the entire application, thesurface active material may form a continuous or contiguous network of athin film of the surface active material.

Supercapacitor Electrodes Comprising Frustules Having Formed ThereonManganese Oxide as Surface Active Material

An surface active material for a supercapacitor electrode, e.g., anelectrode configured to give rise to pseudo capacitance, may include oneor more manganese-containing compounds, e.g., a manganese oxide,described above. The manganese-containing compound may have acomposition and be prepared using any relevant method, for example asdescribed herein. According to some embodiments, one or more electrodescomprise frustules having formed thereon a manganese oxide (MnO),x_(y)e.g., manganese oxide nanostructures, as the surface active material. Insome embodiments, the frustules have surfaces that are coated withmanganese oxide nanostructures in any manner described herein. Frustulescoated with manganese oxide, e.g., manganese oxide nanoparticles, mayconstitute about 50-95 wt. %, 55-85 wt. %, 60-80 wt. %, 65- 75 wt. %, ora value in a range defined by any of these values, for instance about 70wt. %, on the basis of the total weight of the electrode, e.g., asprinted and dried.

The one or more electrodes comprising manganese oxide can additionallycomprise an electrically conducting material as described above. Theelectrically conducting material can include, e.g., conductive carbon inthe amount of about 0.1-15 wt. %, 1-13 wt. %, 3-11 wt. %, 5-9 wt. %, 6-8wt. %, for instance about 7 wt. %, on the basis of the total weight ofthe electrode, e.g., as printed and dried. The conductive carbon formspart of the electrode to provide electrical conductivity as describedabove. The conductive carbon can improve printability of inks. Theconductive carbon can increase flexibility of the resultingsupercapacitor. One example of conductive carbon that can be included aspart of the one or more electrodes is Timcal Super 65®, sold by TimcalGraphite & Carbon (Switzerland).

The one or more electrodes comprising manganese oxide can additionallycomprise carbon nanotubes in the amount of about 0.1-15 wt. %, 1-13 wt.%, 3-11 wt. %, 5-9 wt. %, 6-8 wt. %, for instance about 7 wt. %, on thebasis of the total weight of the electrode, e.g., as printed and dried.The carbon nanotubes serve as part of the electrode to provideelectrical conductivity. The carbon nanotubes can improve printabilityof inks. The carbon nanotubes can increase flexibility of the resultingsupercapacitor. One example of carbon nanotubes that can be included aspart of the one or more electrodes is multiwalled carbon nanotubes, soldby Cheap Tubes Inc. (United States).

The one or more electrodes comprising manganese oxide can additionallycomprise a polymer binder in the amount of about 0.1-15 wt. %, 0.5-12wt. %, 1-9 wt. %, 2-6 wt. %, 3-5 wt. %, for instance about 4 wt. %, onthe basis of the total weight of the electrode, e.g., as printed anddried. The polymer binder promotes adhesion to substrates and otherlayers and integrity of the layers (e.g., hold particles together). Oneexample of polymer binder that can be included as part of the one ormore electrodes is polyvinylidene fluoride (PVDF), sold by Solef 5130(Belgium). [0469] The one or more electrodes comprising manganese oxidecan additionally comprise an electrolyte comprising an ionic liquid. Theionic liquid may be present in the amount of about 5-30 wt. %, 8-27 wt.%, 11-24 wt. %, 14-21 wt. %, 17-20 wt. %, for instance about 18 wt. %,on the basis of the total weight of the electrode, e.g., as printed anddried. The ionic liquid can serve as an electrolyte or be part of anelectrolyte. One example of ionic liquid that can be included as part ofthe one or more electrodes is 1-ethyl-3-methylimidazoliumtetrafluoroborate (C₂mimBF₄), sold by IoLitec (Germany).

The one or more electrodes comprising manganese oxide can additionallycomprise a salt, which may be dissolved in the solvent or the ionicliquid in the amount of about 0.1-5 wt. %, 1-5 wt. %, 1.5-4.5 wt. %,2.0-4.0 wt. %, 2.5-3.5 wt. %, for instance about 3 wt. %, on the basisof the total weight of the electrode, e.g., as printed and dried. Thesalt serves as an additive to improve ionic conductivity. The salt canpromote higher capacitance by contributing to interface structure. Oneexample of ionic liquid that can be included as part of the one or moreelectrodes is 1-ethyl-3-methylimidazolium tetrafluoroborate (C₂mimBF₄),sold by IoLitec (Germany). The salt and the ionic liquid that can beincluded as part of the one or more electrodes can be any salt or anyionic liquid described herein.

In some embodiments, in addition to an ionic liquid or a combination ofan ionic liquid and a salt, the one or more electrodes comprisingmanganese oxide may comprise a solvent of the electrolyte that may beresidual after drying.

In some embodiments, the one or more electrodes comprise a gel thatserves as a medium for ion transportation. The gel can include theelectrolyte, which can include one or more of a solvent, salt and anionic liquid, and a suitable gel-forming or a gelling polymer, asdescribed herein.

In some embodiments, the gel can at least partially fill the network ofpores in the frustules. When the gel substantially entirely fills thenetwork of pores, the resulting electrode may be substantially free ofpores comprising voids. On the other hand, when the gel partially fillsthe network of pores, the resulting separator may still include somepores comprising voids. The voids, when present, may be filled with theelectrolyte.

In some configurations, once it fills the network of pores in thefrustules, the gel including the electrolyte may remain relativelylocalized without freely moving through the network of pores in thefrustules.

Supercapacitor Electrodes Comprising Frustules and Zine Oxide as SurfaceActive Material

An active material for a supercapacitor electrode, e.g., an electrodeconfigured to give rise to pseudo capacitance, includes one or morezinc-containing compounds, e.g., a zinc oxide, described above. Thezinc-containing compound may have a composition and be prepared usingany relevant method described herein. According to some embodiments, oneor more electrodes comprise frustules having formed thereon a zinc oxide(Zn_(x)O_(y), e.g., ZnO), e.g., zinc oxide nanostructures, as thesurface active material. In some embodiments, the frustules havesurfaces that are coated with zinc oxide nanostructures in any mannerdescribed herein. Frustules coated with zinc oxide, e.g., zinc oxidenanoparticles, can constitute about 25-90 wt. %, 30-80 wt. %, 35-70 wt.%, 40-60 wt. %, 45-50 wt. % or a value in a range defined by any ofthese values, for instance about 46 wt. %, on the basis of the totalweight of the electrode, e.g., as printed and dried.

The one or more electrodes comprising zinc oxide can additionallycomprise an electrically conducting material as described above. Theelectrically conducting material can include, e.g., conductive carbon inthe amount of about 0.1-15 wt. %, 2-14 wt. %, 4-13 wt. %, 6-12 wt. %,8-11 wt. %, for instance about 10 wt. %, on the basis of the totalweight of the electrode, e.g., as printed and dried. The conductivecarbon can form part of the electrode to provide electricalconductivity. The conductive carbon can improve printability of inks.The conductive carbon can increase flexibility of the resultingsupercapacitor. The conductive carbon can serve as part of the electrodeto provide electrical conductivity as described above. The conductivecarbon can improve printability of inks. The conductive carbon canincrease flexibility of the resulting supercapacitor. One example ofconductive carbon that can be included as part of the one or moreelectrodes is Timcal Super 65®, sold by Timcal Graphite & Carbon(Switzerland).

The one or more electrodes comprising zinc oxide can additionallycomprise carbon nanotubes in the amount of about 0.1-15 wt. %, 0.1-11wt. %, 0.1-7 wt. %, 0.1-5 wt. %, 1-3 wt. %, for instance about 2 wt. %,on the basis of the total weight of the electrode, e.g., as printed anddried. The carbon nanotubes can serve as part of the electrode toprovide electrical conductivity. The carbon nanotubes can improveprintability of inks. The carbon nanotubes can increase flexibility ofthe resulting supercapacitor. One example of carbon nanotubes that canbe included as part of the one or more electrodes is multi-walled carbonnanotubes, sold by Cheap Tubes Inc. (United States).

The one or more electrodes comprising zinc oxide can additionallycomprise a polymer binder in the amount of about 0.1-15 wt. %, 0.5-13wt. %, 1-11 wt. %, 2-9 wt. %, 3-7 wt. %, for instance about 5 wt. %, onthe basis of the total weight of the electrode, e.g., as printed anddried. The polymer binder can promote adhesion to substrates and otherlayers and integrity of the layers (e.g., hold particles together). Oneexample of polymer binder that can be included as part of the one ormore electrodes is polyvinylidene fluoride (PVDF), sold by Solef 5130(Belgium).

The one or more electrodes comprising zinc oxide can additionallycomprise an electrolyte comprising an ionic liquid. The ionic liquid maybe present in the amount of about 10-50 wt. %, 15-50 wt. %, 20-45 wt. %,25-40 wt. %, 30-35 wt. %, for instance about 34 wt. %, on the basis ofthe total weight of the electrode, e.g., as printed and dried. The ionicliquid can serve as an electrolyte or be part of an electrolyte. Oneexample of ionic liquids that can be included as part of the one or moreelectrodes is 1-ethyl-3-methylimidazolium tetrafluoroborate (C₂mimBF₄),sold by IoLitec (Germany).

The one or more electrodes comprising zinc oxide can additionallycomprise a salt, which may be dissolved in the ionic liquid in theamount of about 0.1-5 wt. %, 1-5 wt. %, 1.5-4.5 wt. %, 2.0-4.0 wt. %,2.5-3.5 wt. %, for instance about 3 wt. %, on the basis of the totalweight of the electrode, e.g., as printed and dried. The salt can serveas an additive to improve ionic conductivity. The salt can promotehigher capacitance by contributing to interface structure. One exampleof ionic liquids that can be included as part of the one or moreelectrodes is 1-ethyl-3-methylimidazolium tetrafluoroborate (C₂mimBF₄),sold by IoLitec (Germany).

In some embodiments, in addition to an ionic liquid or a combination ofan ionic liquid and a salt, the one or more electrodes comprising zincoxide may comprise a solvent of the electrolyte that may be residualafter drying.

Supercapacitor Electrodes Comprising Frustules Having Formed ThereonCarbon Nanostructures as Surface Active Material

An active material for a supercapacitor electrode, e.g., an electrodeconfigured to give rise to EDCL, includes one or more carbonnanostructures, e.g., CNT as described above. The carbon nanostructuresmay have a composition and be prepared using any relevant methoddescribed herein. According to some embodiments, one or more electrodescomprise frustules having formed thereon carbon structures, e.g., carbonnanostructures, as the surface active material. In some embodiments, thefrustules have surfaces that are coated with carbon nanostructures,e.g., CNTs, in any manner described above. The one or more electrodescomprise CNTs in the amount of about 1-50 wt. %, 1-40 wt. %, 1-30 wt. %,1-20 wt. %, 5-15 wt. %, for instance about 11 wt. %, on the basis of thetotal weight of the electrode, e.g., as printed and dried. The carbonnanotubes can serve as part of the surface active material. The carbonnanotubes can provide printability of inks. The carbon nanotubes canincrease flexibility of the resulting supercapacitor. One example ofcarbon nanotubes that can be included as part of the one or moreelectrodes is multiwall carbon nanotubes, sold by Cheap Tubes Inc.(United States).

The one or more electrodes comprising carbon can additionally comprisean electrically conducting material as described above. The electricallyconducting material can include, e.g., conductive carbon in the amountof about 1-50 wt. %, 1-40 wt. %, 1-30 wt. %, 1-20 wt. %, 5-15 wt. %, forinstance about 11 wt. %, on the basis of the total weight of theelectrode, e.g., as printed and dried. The conductive carbon can formpart of the surface active material. The conductive carbon can provideprintability of inks. The conductive carbon can increase flexibility ofthe resulting supercapacitor. One example of conductive carbon that canbe included as part of the one or more electrodes is Timcal Super 65®,sold by Timcal Graphite & Carbon (Switzerland).

The one or more electrodes comprising CNTs can additionally comprisepolymer binder in the amount of about 0.1-15 wt. %, 1-13 wt. %, 3-11 wt.%, 5-9 wt. %, for instance about 7 wt. %, on the basis of the totalweight of the electrode, e.g., as printed and dried. The polymer bindercan promote adhesion to substrates and other layers and integrity of thelayers (e.g., hold particles together). One example of polymer binderthat can be included as part of the one or more electrodes ispolyvinylidene fluoride (PVDF), sold by Solef 5130 (Belgium).

The one or more electrodes comprising CNTs can additionally compriseionic liquid in the amount of about 10-90 wt. %, 30-85 wt. %, 50-80 wt.%, 70-75 wt. %, for instance about 71 wt. %, on the basis of the totalweight of the electrode, e.g., as printed and dried. The ionic liquidcan serve as an electrolyte or be part of an electrolyte. One example ofionic liquids that can be included as part of the one or more electrodesis 1-ethyl-3-methylimidazolium tetrafluoroborate (C₂mimBF₄), sold byIoLitec (Germany).

The one or more electrodes comprising CNTs can additionally comprise asalt, which may be dissolved in the ionic liquid in the amount of about0.1-5 wt. %, 1-5 wt. %, 1.5-4.5 wt. %, 2.0-4.0 wt. %, 2.5-3.5 wt. %, forinstance about 3 wt. %, on the basis of the total weight of theelectrode, e.g., as printed and dried. The salt can serve as an additiveto improve ionic conductivity. The salt can promote higher capacitanceby contributing to interface structure. One example of ionic liquidsthat can be included as part of the one or more electrodes is1-ethyl-3-methylimidazolium tetrafluoroborate (C₂mimBF₄), sold byIoLitec (Germany). The salt and the ionic liquid that can be included aspart of the one or more electrodes can be any salt or any ionic liquiddescribed herein.

In some embodiments, in addition to an ionic liquid or a combination ofan ionic liquid and a salt, the one or more electrodes comprising CNTmay comprise a solvent of the electrolyte that may be residual afterdrying.

Supercapacitor Separators

According to various embodiments, supercapacitors further comprise aseparator. The separator, which may be interposed between theelectrodes, can inhibit or prevent an electrical short that may resultfrom a direct contact between the electrodes. The separator may includefrustules. The separator may be configured to serve as a permeablemembrane for ion transportation. Frustule-containing separators canprovide lower electrical resistance, chemical stability and/orrelatively small thickness. The frustules serve as a separator fillermaterial and to improve printability, e.g., by inhibiting or preventingholes from forming during printing, thereby shorting the electrodes.

Frustule-containing separators can have any structure and composition,and can be prepared using any method described herein.

Referring to FIGS. 14A, 14B and 15 , each of the supercapacitors 1400,1500 comprises a separator 1430 comprising frustules, e.g., purifiedfrustules that constitute about 10-70 wt. %, 13-55 wt. %, 16-45 wt. %,19-35 wt. %, 20-25 wt. % or a value in a range defined by any of thesevalues, for instance about 22 wt. %, on the basis of the total weight ofthe separator, e.g., as printed and dried. Various characteristics andprocesses of forming purified frustules and a separator therefrom aredescribed above.

The separator 1430 comprising frustules can additionally comprise athermally conductive additive in the amount of about 0.1-5 wt. %, 0.5-4wt. %, 1-3 wt. %, 1.5-2.5 wt. %, for instance about 2 wt. %, on thebasis of the total weight of the separator, e.g., as printed and dried.The thermally conductive additive may serve as a separator filler. Thethermally conductive additive may serve as a heat absorbing and/orconducting agent, e.g., as a near infrared radiation (NIR) absorbingagent. As described herein, a NIR radiation may have a wavelength of 0.7μm to 2.5 mm. The thermally conducive additive may efficiently absorband/or conduct heat during fabrication, e.g., during a drying processusing near infrared radiation (NIR). The thermally conductive additivemay reduce the internal resistance of the supercapacitor, therebyimproving the power. The thermally conductive additive may, e.g., be agood heat absorber, a good thermal conductor and a relatively goodelectrical insulator. One example of such thermally conductive additivesthat can be included as part of the separator is graphene oxide (GO),sold by Cheap Tubes Inc. (U.S.A). The inventors have found that, whengraphene oxide is added to the ink for printing the separator, theresulting ink showed improved printability, superior heat conductionduring drying (which reduces drying time) and relatively lower internalresistance of the supercapacitor, although not all such advantages arenecessary. In addition, because the thermally conductive additive suchas GO can be a good electrical insulator, the separator advantageouslymaintains the electrically insulating characteristics. In someembodiments, GO comprises sheets of GO that contact each other to form anetwork of contiguous GO sheets. The inventors have found, when includedas part of a printed layer such as a printed separator layer, GO mayreduce the drying time by as much as one order of magnitude, e.g., fromtens or minutes to tens of seconds.

The separator comprising frustules can additionally comprise a polymerbinder in the amount of about 5-20 wt. %, 5-15 wt. %, 5-10 wt. %, 6-8wt. %, for instance about 7 wt. %, on the basis of the total weight ofthe separator, e.g., as printed and dried. The polymer binder canpromotes adhesion to substrates and other layers and integrity of thelayers (e.g., hold particles together). One example of polymer binderthat can be included as part of the separator is polyvinylidene fluoride(PVDF), sold by Solef 5130 (Belgium).

The separator comprising frustules can additionally comprise a gellingpolymer in the amount of about 0.5-10 wt. %, 1.0-7.0 wt. %, 1.5-5.0 wt.%, 2.0-4.0 wt. %, for instance about 3 wt. %, on the basis of the totalweight of the separator, e.g., as printed and dried. The gelling polymermay form a gel with an ionic liquid. One example of the gelling polymerthat can be included as part of the separator is polyethylene glycol,sold by Sigma Aldrich (U.S.A.).

In some embodiments, the gelling polymer forms gel that serves as amedium for ion transportation. The gel can fill the network of pores inthe frustules. The gel can include the electrolyte, which can includeone or more of a solvent, salt and an ionic liquid, and a suitablegel-forming or a gelling polymer, as described herein.

In some embodiments, the gel can at least partially fill the network ofpores in the frustules. When the gel substantially entirely fills thenetwork of pores, the resulting separator may be substantially free ofpores comprising voids. Advantageously, the separator that issubstantially free of pores can be effective in preventing undesirablemovement of particles therethrough, which may be particularlyadvantageous in the context of printed layers having various components,e.g., frustules and/or nanostructures, that can become loose andseparated.

On the other hand, when the gel partially fills the network of pores,the resulting separator may still include some pores comprising voids,which may be filled with electrolyte. Advantageously, such configurationmay increase ionic conductivity for higher power.

In some configurations, once it fills the network of pores in thefrustules, the gel including the electrolyte may remain relativelylocalized without freely moving through the network of pores in thefrustules.

The separator comprising frustules can additionally comprise anelectrolyte, which may include an ionic liquid. The ionic liquid may bepresent in the amount of about 10-80 wt. %, 30-75 wt. %, 50-70 wt. %,55-65 wt. %, for instance about 60 wt. %, on the basis of the totalweight of the separator, e.g., as printed and dried. The ionic liquidcan serve as an electrolyte or be part of an electrolyte. One example ofionic liquid that can be included as part of the separator is1-ethyl-3-methylimidazolium tetrafluoroborate (C₂mimBF₄), sold byIoLitec (Germany).

The separator comprising frustules can additionally comprise a salt,which may be dissolved in the electrolyte, in the amount of about 0.1-8wt. %, 1-7.5 wt. %, 3.0-7.0 wt. %, 5.0-6.5 wt. %, 5.5-6.5 wt. %, forinstance about 6 wt. %, on the basis of the total weight of theseparator, e.g., as printed and dried. The salt can serve as an additiveto improve ionic conductivity. The salt can promote higher capacitanceby contributing to interface structure. One example of the salt that canbe included as part of the one or more electrodes is zinctetrafluoroborate Zn(BF₄)₂, sold by Sigma Aldrich (U.S.A).

As described above, various components including one or more of theelectrodes and the separator of the supercapacitor may advantageously beprinted using a ink. In the following, compositions of inks that can beused to print the one or more of the electrodes and the separator aredescribed.

Advantageously, when printed, the thicknesses of each of the electrodesand the separator can be made extremely thin. Each of the separator andthe electrodes can have a thickness of 10-50 microns, 50-100 microns,100-200 microns, 200-300 microns, 300-400 microns, 400-500 microns, or athickness in a range defined by any of these values.

Composition and Method of Preparing Printable Manganese Oxide-ContainingInk for Supercapacitor Electrodes

As described above, one of the possible advantages of thesupercapacitors described herein includes the relative ease and lowercost of manufacturing, arising from printability of one or more layersof the supercapacitors, including the electrodes. According to variousembodiments, a manganese oxide-containing ink that can be used to formone or more electrodes of the supercapacitor can include any componentor composition, and may be prepared using any method of preparingMn_(x)O_(y)-based inks described elsewhere herein. In some embodiments,prior to printing and drying, the manganese oxide-containing inkincludes various components of the manganese oxide-containing electrodedescribed above in the amount of about 20-70 wt. %, 25-60 wt. %, 30-50wt. %, 30- 40 wt. %, or a value in a range defined by any of thesevalues, for instance about 34 wt. %, on the basis of the total weight ofthe manganese oxide-containing ink.

Prior to printing and drying, the manganese oxide-containing inkincludes a solvent, which may constitute the balance of the manganeseoxide-containing ink. The manganese oxide-containing ink includes thesolvent in the amount of about 30-80 wt. %, 40-75 wt. %, 50-70 wt. %,60-70 wt. %, or a value in a range defined by any of these values, forinstance about 66 wt. %, on the basis of the total weight of themanganese oxide-containing ink. One example solvent isn-methylpyrrolidone.

The manganese oxide-containing ink may be prepared according to thefollowing example method. A solvent, an ionic liquid and carbonnanotubes (CNTs) are mixed, e.g., in a vial, and the resulting mixturemay be sonicated, e.g., for 1-15 min., to disperse the CNTs. Themanganese oxide-coated frustules are added, and the mixture may bestirred, e.g., for 5-30 min. at 50-150° C. on a hot plate. The mixturemay be further mixed in a planetary centrifugal mixer (for example,THINKY, USA) for 1-10 min. at 500-2000 rpm. Conductive carbon can beadded and mixed next, followed by lab egg mixing for 1-15 min. at 150°C. Subsequently, a polymer, which may be dissolved in or mixed with asolvent, can be added, and the mixture can be stirred with lab eggstirrer with heat for 5-30 min. on a hot plate at 50-150° C. The mixturecan be further mixed, e.g., on a hot plate and/or on a planetarycentrifugal mixer for 1-15 min. at 500-2000 rpm.

Composition and Method of Preparing Printable Zinc Oxide-Containing Inkfor Supercapacitor Electrodes

According to various embodiments, a zinc oxide-containing ink that canbe used to form one or more electrodes of the supercapacitor can includeany component or composition, and be prepared using any method ofpreparing ZnO-based inks described herein. In some embodiments, prior toprinting and drying, the zinc oxide-containing ink includes variouscomponents of the zinc oxide-containing electrode described above in theamount of about 20-70 wt. %, 25-60 wt. %, 25-50 wt. %, 25-40 wt. %, or avalue in a range defined by any of these values, for instance about 29wt. %, on the basis of the total weight of the zinc oxide-containingink.

Prior to printing and drying, the zinc oxide-containing ink includes asolvent, which may constitute the balance of the zinc oxide-containingink. The zinc oxide-containing ink can include the solvent in theamount, of about 30-80 wt. %, 40-75 wt. %, 50-75 wt. %, 60-75 wt. %, ora value in a range defined by any of these values, for instance about 71wt. %, on the basis of the total weight of the zinc oxide-containingink. One example of a solvent includes n-methylpyrrolidone.

The zinc oxide-containing ink may be prepared according to the followingexample method. A solvent, an ionic liquid and carbon nanotubes (CNTs)are mixed, e.g., in a vial, and the resulting mixture may be sonicated,e.g., for 1-15 min., to disperse the CNTs. The zinc oxide-coated diatomsare added and the mixture is stirred, e.g., for 1-15 min. at 50-150° ona hot plate, and mixed, e.g., on a planetary centrifugal mixer for 1-15min. at 500-2000 rpm. Conductive carbon can be added and mixed next, for1-15 min. on the hotplate at 50-150° C. Subsequently, a polymer, whichmay be dissolved in or mixed with a solvent, can be added, and themixture is stirred for 1-15 min. at 50-150° C. The mixture can befurther mixed, e.g., on a hot plate and/or on a planetary centrifugalmixer for 1-15 min. at 500-2000 rpm.

Composition and Method of Preparing Printable Carbon Nanotube-ContainingInk for Supercapacitor Electrodes

According to various embodiments, a carbon nanotube (CNT)-containing inkthat can be used to form one or more electrodes of the supercapacitorcan include any component or composition, and be prepared using anymethod of preparing CNT-based inks described herein. In someembodiments, prior to printing and drying, the CNT-containing ink caninclude various components of the CNT-containing electrode describedabove in the amount of about 10-80 wt. %, 10-60 wt. %, 10-40 wt. %,10-30 wt. %, or a value in a range defined by any of these values, forinstance about 18 wt. %, on the basis of the total weight of theCNT-containing ink.

Prior to printing and drying, the CNT-containing ink can include asolvent, which may constitute the balance of the CNT-containing ink. TheCNT-containing ink can include the solvent in the amount of about 10-80wt. %, 10-60 wt. %, 10-40 wt. %, 10-30 wt. %, or a value in a rangedefined by any of these values, for instance about 18 wt. %, on thebasis of the total weight of the CNT-containing ink. One example of asolvent includes n-methylpyrrolidone.

The CNT-containing ink may be prepared according to the following oneexample method. Solvent, ionic liquid and CNTs are mixed together, e.g.,in a vial. The resulting mixture may be sonicated for 1-15 min. todisperse the CNTs. Conductive carbon may subsequently be added andmixed, e.g., for 1-15 min. on the hotplate at 50-150° C. Subsequently, apolymer, which may be dissolved in or mixed with a solvent, may be addedand the mixture may be stirred, e.g., for 1-15 min at 50-150° C. on ahot plate. The mixture can be further mixed on a planetary centrifugalmixer for 1-15 min. at 500-2000 rpm.

Composition and Method of Preparing Printable Frustule-Containing Inkfor Supercapacitor Separators

According to various embodiments, a frustule-containing ink that can beused to form a separator of the supercapacitor can include any componentor composition, and can be prepared using any method of preparingfrustule-based inks described herein. In some embodiments, prior toprinting and drying, the frustule-containing ink includes variouscomponents of the frustule-containing electrode described above in theamount of about 20-80 wt. %, 30-70 wt. %, 40-60 wt. %, 50-60 wt. %, or avalue in a range defined by any of these values, for instance about 54wt. %, on the basis of the total weight of the frustule-containing ink.

Prior to printing and drying, the frustule-containing ink includes asolvent, which may constitute the balance of the frustule-containingink. The frustule-containing ink can include the solvent in the amount,of about 20-80 wt. %, 30-70 wt. %, 40-60 wt. %, 40-50 wt. %, or a valuein a range defined by any of these values, for instance about 46 wt. %,on the basis of the total weight of the frustule-containing ink. Oneexample solvent is tetramethyl urea.

The frustule-containing ink may be prepared according to the followingexample method. A gelling polymer and a binder polymer are dissolved ina solvent, e.g., at 50-150° C. on a hot plate. Graphene oxide may bemixed with an electrolyte and a solvent. The graphene oxide mixture maybe sonicated for 1-15 min. and mixed with the dissolved polymers.Subsequently, the purified diatoms are added and the mixture may bestirred at 50-150° C. on the hot plate for 5-60 min.

Example Components of Printable Inks for Supercapacitor Electrodesand/or Separators

Printable inks for printing one or more layers of a supercapacitor,e.g., electrode and/or separator layers, can include purified diatomfrustules, which may have any structure and composition and be preparedusing any method as described herein. According to some embodiments, thepurified diatom frustules may be substantially unmodified (e.g., thechemical composition of purified diatom frustules may have substantiallythe same composition as the frustules in natural form).

Printable inks for printing one or more electrode layers, e.g.,electrode layers configured as a pseudo capacitor, can comprise diatomfrustules coated with a zinc oxide (ZnO), diatom frustules coated with amanganese oxide (Mn_(x)O_(y) including, e.g., MnO, Mn₂O₃, Mn₃O₄, MnOOHand MnO₂ and their mixtures), which may have any component, compositionand be prepared using any method as described herein.

Printable inks for printing one or more electrode layers, e.g.,electrode layers configured as a pseudo capacitor or as an EDLC, cancomprise diatom frustules coated with carbon nanotubes (CNTs), which mayinclude any component or composition, and be prepared using anypreparation method described herein. For example, CNTs included in theinks may include one or more of any of a variety of forms of CNTs,including multi wall, single wall, double wall, metallic andsemiconducting, among other forms of CNTs.

Printable inks for printing one or more electrode layers, e.g.,electrode layers configured as a pseudo capacitor or as an EDLC, cancomprise one or more conductive carbon, which may include any componentor composition and be prepared using any preparation method describedherein. For example, conductive carbon included in the inks may includeone or more of graphene, graphite, carbon nano-onions, carbon black,carbon fibers, carbon nanofibers, amorphous carbon, activated carbon,charcoal, carbon buckyballs, carbon nanobuds, and pyrolytic carbon,among other forms of conductive carbon.

Printable inks for printing a separator can comprise one or morethermally conductive additives, e.g., graphene oxide. As describedherein, graphite is a three-dimensional carbon based material made up ofmillions of layers of graphene, as understood in the relevant industry.Graphite oxide refers to a material formed by oxidation of graphiteusing strong oxidizing agents, thereby introducing oxygenatedfunctionalities to graphite. For example, graphite oxide may expand thelayer separation, or make the material hydrophilic. Graphite oxide canbe exfoliated, e.g., in water using sonication, thereby producing atwo-dimensional material comprising a single or a few layers of graphiteoxide, which is referred to in the industry and herein a graphene oxide(GO). According to various embodiments described herein, GO refers to astructure having one or more layers but fewer than about 100, 50, 20, 10or 5 sheets, any number of sheets within a range defined by any of thesevalues.

According to various embodiments, GO can have a carbon-to-oxide ratiobetween about 1 to 100, 1 to 2, 2 to 5, 5 to 10, 10 to 15, 15 to 20, 20to 25, 25 to 30, 30 to 35, 35 to 40, 40 to 45, 45 to 50, 50 to 55, 55 to60, 60 to 65, 65 to 70, 70 to 75, 75 to 80, 80 to 85, 85 to 90, 90 to95, 95 to 100, or a ratio within a range defined by any of these values.For instance, according to some embodiments, GO sheets have a meancarbon-to-oxygen ratio of about 2:1 to about 20:1 or about 5:1 to about20:1.

Other embodiments of thermally conductive additives are possible. Forexample, the conductive additives can include one or more of boronnitride, beryllium oxide and other thermally conductive dielectricmaterials.

Various materials included in the inks for forming the layers of thesupercapacitor, including coated diatoms, CNTs, conductive carbons,thermally conductive additives can have particle size ranging from 1 nmto 100 microns.

Printable inks for printing one or more layers of a supercapacitor,e.g., an electrode and/or a separator layers, can include a binder. Thebinder can include any component and composition of binders in the inksand electrodes as described herein. Examples of binders that can be usedinclude styrene butadiene rubber (SBR), polyvinyl pyrrolidone (PVP),polyvinylidene fluoride, polyvynylidene fluoride-trifluoroethylene,polytetrafluoroethylene, polydimethylsiloxane, polyethelene,polypropylene, polyethylene oxide, polypropylene oxide, polyethyleneglycolhexafluoropropylene, polyethylene terefphtalatpolyacrylonitryle,polyvinyl butyral, polyvinylcaprolactam, polyvinyl chloride; polyimidepolymers and copolymers (including aliphatic, aromatic and semi-aromaticpolyimides), polyamides, polyacrylamide, acrylate and (meth)acrylatepolymers and copolymers such as polymethylmethacrylate,polyacrylonitrile, acrylonitrile butadiene styrene, allylmethacrylate,polystyrene, polybutadiene, polybutylene terephthalate, polycarbonate,polychloroprene, polyethersulfone, nylon, styrene-acrylonitrile resin;polyethylene glycols, clays such as hectorite clays, garamite clays,organomodified clays; saccharides and polysaccharides such as guar gum,xanthan gum, starch, butyl rubber, agarose, pectin; celluloses andmodified celluloses such as hydroxyl methylcellulose, methylcellulose,ethyl cellulose, propyl methylcellulose, methoxy cellulose, methoxymethylcellulose, methoxy propyl methylcellulose, hydroxy propylmethylcellulose, carboxy methylcellulose, hydroxy ethylcellulose, ethylhydroxyl ethylcellulose, cellulose ether, cellulose ethyl ether,chitosan as well as their polymeric precursors or polymerizableprecursors.

Printable inks for printing one or more layers of a supercapacitor,e.g., electrode and/or separator layers, can include a gelling polymer.The gelling polymer can include any component and composition of gellingpolymers in the inks and electrodes as described herein. Examples ofgelling polymers that can be used include polyvinylidene fluoride,polyacrylic acid, polyethylene oxide, polyvinyl alcohol.

According to various embodiments, all polymers included in the inks havesuitable chemical, thermal and electrochemical stability such that theycan be formed into printed layers.

Electrolytes for Supercapacitors

The energy density (E) of supercapacitors can be expressed asE=CV²/2,  Eq. 7where C is the capacitance and V is the voltage. The voltage to whichsupercapacitors can be charged depends on, among other things, theelectrochemical potential window of the electrolyte. Because of thestrong dependence of energy density on voltage (proportional to squareroot of voltage), the electrochemical potential windows of electrolytescan have a substantial impact on the energy density, sometimes a largerimpact on the energy density than the capacitance.

Operating electrochemical potential windows of typical aqueouselectrolytes is 1-1.3V (hydrogen/oxygen evolution occur if one exceedsthis voltage). Organic based electrolytes can have potential windows of2.5-2.7V. To obtain significantly higher potential windows, e.g.,3.5-4.5V or even higher, electrolytes according to some embodimentsinclude ionic liquids.

According to various embodiments, the electrolytes included in thesupercapacitors have wide electrochemical potential window (for higherenergy density), have higher ionic conductivity (low resistance andhigher power), have higher chemical stability to other components, havewide temperature operating range, have low volatility and flammability,are environmentally friendly and/or are lower in cost, among otherpossible advantages.

As described herein, an electrolyte includes an electrolyte salt (oracid, base) and a solvent. The solvent can be aqueous or organic.Advantageously, solvents can have relatively high boiling point (above80° C.). The solvents according to embodiments also have relatively slowevaporation rate to reduce solvent loss during ink mixing and printingas well as influencing the ink shelf life. The slow evaporation ratealso increases lifetime of the supercapacitor. The solvents may beselected to dissolve various polymers described above, or serve as amedium for forming polymer suspensions as part of inks. The solvents maybe selected to improve rheology of the inks. The remnants of somesolvents in dried layers can improve the electrical performance of thesupercapacitor.

To achieve these and/or other advantages, solvents can include one ormore of water and alcohols such as methanol, ethanol, N-propanol(including 1-propanol, 2-propanol (isopropanol or IPA), 1-methoxy-2-propanol), butanol (including 1-butanol, 2-butanol (isobutanol)),pentanol (including 1- pentanol, 2- pentanol, 3- pentanol), hexanol(including 1-hexanol, 2-hexanol, 3- hexanol), octanol, N-octanol(including 1-octanol, 2-octanol, 3-octanol), tetrahydrofurfuryl alcohol(THFA), cyclohexanol, cyclopentanol, terpineol; lactones such as butyllactone; ethers such as methyl ethyl ether, diethyl ether, ethyl propylether, and polyethers; ketones, including diketones and cyclic ketones,such as cyclohexanone, cyclopentanone, cycloheptanone, cyclooctanone,acetone, benzophenone, acetylacetone, acetophenone, cyclopropanone,isophorone, methyl ethyl ketone; esters such ethyl acetate, dimethyladipate, propylene glycol monomethyl ether acetate, dimethyl glutarate,dimethyl succinate, glycerin acetate, carboxylates; carbonates such aspropylene carbonate; polyols (or liquid polyols), glycerols and otherpolymeric polyols or glycols such as glycerin, diol, triol, tetraol,pentanol, ethylene glycols, diethylene glycols, polyethylene glycols,propylene glycols, dipropylene glycols, glycol ethers, glycol etheracetates 1,4-butanediol, 1,2-butanediol, 2,3-butanediol,1,3-propanediol, 1,4-butanediol, 1,5- pentanediol, 1,8-octanediol,1,2-propanediol, 1,3-butanediol, 1,2-pentanediol, etohexadiol,p-menthane-3,8-diol, 2-methyl-2,4-pentanediol; tetramethyl urea,n-methylpyrrolidone, acetonitrile, tetrahydrofuran (THF), dimethylformamide (DMF), N-methyl formamide (NMF), dimethyl sulfoxide (DMSO);thionyl chloride; sulfuryl chloride; dibasic ester, diethylene glycolmonoethyl ether acetate, combinations thereof, and the like.

Organic solvents can include one or more of acetonitrile, propylenecarbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate,ethyl acetate, 1,1,1,3,3,3-hexafluoropropan-2-ol, adiponitrile,1,3-propylene sulfite, butylene carbonate, Y-Butyrolactone,Y-Valerolactone, propionitrile, glutaronitrile, adiponitrile,methoxyacetonitrile, 3-methoxypropionitrile, N,N-Dimethylformamide,N,N-Dimethylacetamide, N-Methylpyrrolidinone, N-Methyloxazolidinone,N,N″-Dimethylimidazolininone, nitromethane, nitroethane, sulfonate,3-Methylsulfonate, dimethylsulfoxide, trimethyl phosphate, combinationsthereof, and the like.

Electrolytes according to some embodiments include ionic liquids (ILs).As described herein, IL refers to a salt in the liquid state atoperation temperatures of the supercapacitors. For example, withoutlimitation, IL can be in the liquid molten form at temperature below100° C. Some ILs can consist essentially of ions, including a cation andan anion. The ILs can include combinations of the following examplecations and anions.

Examples of cations that can be included in the ILs for supercapacitorsinclude butyltrimethylammonium, 1-ethyl-3-methylimidazolium,1-butyl-3-methylimidazolium, 1-methyl-3-propylimidazolium,1-hexyl-3-methylimidazolium, choline, ethylammonium,tributylmethylphosphonium, tributyl(tetradecyl)phosphonium,trihexyl(tetradecyl)phosphonium, 1-ethyl-2,3-methylimidazolium,1-butyl-1-methylpiperidinium, diethylmethylsulfonium,1-methyl-3-propylimidazolium, 1-ethyl-3-methylimidazolium,1-methyl-1-propylpiperidinium, 1-butyl-2-methylpyridinium,1-butyl-4-methylpyridinium, 1-butyl-1-methylpyrrolidinium,diethylmethylsulfonium, combinations thereof, and the like.

Examples of anions that can be included in the ILs for supercapacitorsinclude tris(pentafluoroethyl)trifluorophosphate,trifluoromethanesulfonate, hexafluorophosphate, tetrafluoroborate, ethylsulfate, dimethyl phosphate, methansulfonate, triflate,tricyanomethanide, dibutylphosphate, bis(trifluoromethylsulfonyl)imide,bis-2,4,4-(trimethylpentyl) phosphinate, iodide, chloride, bromide,nitrate, combinations thereof, and the like.

According to some embodiments, the electrolyte or the IL of thesupercapacitors additionally includes one or more salts dissolved in theelectrolyte or dissolved in the IL when present. Salts in theelectrolytes include combinations of a cation and an anion.

The cation of the salt can be selected from one or more of zinc, sodium,potassium, magnesium, calcium, aluminum, lithium, barium, combinationsthereof, and the like.

The anion of the salt can be selected from one or more of chloride,bromide, fluoride, bis(trifluoromethanesulfonyl)imide, sulfate,bisulfite, nitrate, nitrite, carbonate, hydroxide, perchloride,bicarbonate, tetrafluoroborate, methansulfonate, acetate, phosphate,citrate, hexafluorophosphate, combinations thereof, and the like.

The electrolyte can include an organic salt, an inorganic salt, an acid,or a base.

Examples of organic salts include tetraethylammonium tetrafluoroborate,tetraethylammonium difluoro(oxalate)borate, methylammoniumtetrafluoroborate, triethylmethylammonium tetrafluoroborate,tetrafluoroboric acid dimethyldi ethylammonium, triethylmethylammoniumtetrafluoroborate, tetrapropylammonium tetrafluoroborate,methyltributylammonium tetrafluoroborate, tetrabutylammoniumtetrafluoroborate, tetrahexylammonium tetrafluoroborate,tetramethylammonium tetrafluoroborate, tetraethyl phosphoniumtetrafluoroborate, tetrapropylphosphonium tetrafluoroborate,tetrabutylphosphonium, tetrafluoroborate, combinations thereof, and thelike.

Examples of acid include H₂SO₄, HCl, HNO₃, HClO₄, combinations thereof,and the like.

Examples of base include KOH, NaOH, LiOH, NH₄OH, combinations thereof,and the like.

Examples of inorganic salts include LiCl, Li₂SO₄, LiClO₄, NaCl, Na₂SO₄,NaNO₃, KCl, K₂SO₄, KNO₃, Ca(NO₃)₂, MgSO₄, combinations thereof, and thelike.

Any other salts, electrolytes or ionic liquids disclosed herein arepossible.

Ionic liquids can serve as the electrolyte and/or be included as part ofthe electrolyte, with or without salts. Ionic liquids can be used withnon-aqueous electrolytes and/or with water.

According to various embodiments, particular electrolytes can beselected to form gel electrolytes by mixing with polymers or othermatrices.

Supercapacitor Configurations

The geometric arrangement of electrodes and the separator ofsupercapacitors according to various embodiments can have any one of theconfigurations illustrated on FIG. 7 . In some embodiments, theelectrodes of the supercapacitor can be arranged symmetrically orasymmetrically. As described herein, when electrodes having opposingpolarities (e.g., cathode and an anode or a positive electrode and anegative electrode) are configured symmetrically, both types ofelectrodes are configured to store charge predominantly as EDLCs orpredominantly as pseudo capacitors.

As described herein, an electrode that is configured to store chargepredominantly through one of the two types of storage mechanismsexhibits a capacitance value that arises predominantly from the type ofstorage mechanisms over the other. For example, when an electrode isconfigured to store energy predominantly through one of the electricdouble layer capacitance or pseudo capacitance mechanisms, at least 80%,90%, 95%, 99%, or a value in a range defined by any of these values, ofthe net capacitance value may arise from the one of the electric doublelayer capacitance or pseudo capacitance mechanisms. For example, whenthe surface active material comprises one but not the other of (1) CNTor (2) manganese oxide and/or zinc oxide, the electrode may bepredominantly configured as one but not the other of an EDLC or a pseudocapacitor. And when the surface active material comprises both (1) CNTand (2) manganese oxide and/or zinc oxide, the electrode may bepredominantly configured as an EDLC when the relative amount ofmanganese oxide and/or zinc oxide is low compared to the relative amountof CNT, and vice versa.

When an electrode is configured to store energy substantially throughboth of the electric double layer capacitance and pseudo capacitancemechanisms, 20-80%, 30-70%, 40-60%, or a value in a range defined by anyof these values, of the net capacitance value may arise from the one ofthe electric double layer capacitance or pseudo capacitance mechanisms,while the balance may substantially be attributable to the other of theelectric double layer capacitance or pseudo capacitance mechanisms. Forexample, when the surface active material comprises both (1) CNT and (2)manganese oxide and/or zinc oxide, the electrode may be substantiallyconfigured as an EDLC as well as a pseudo capacitor when the relativeamounts of both (1) CNT and (2) manganese oxide and/or zinc oxide aresubstantial or effective to give rise to the above percentage values ofcapacitance values attributable to each of the mechanisms.

When electrodes having opposing types polarities (e.g., cathode and ananode or a positive electrode and a negative electrode) are configuredasymmetrically, one of the two types of electrodes is configured tostore charge predominantly as one of a an EDLC or a pseudo capacitor,while the other one of the two types of electrodes is configured tostore charge predominantly as the other of the EDLC or a pseudocapacitor.

When the electrodes of opposite charge types are configuredsymmetrically, the electrodes of both types of charge may includefrustules having nanostructures of the same type. For example,electrodes of both types may include zinc-oxide, e.g., frustules havingformed thereon zinc oxide (Zn_(x)O_(y), e.g., ZnO) nanostructures,manganese-oxide, e.g., frustules having formed thereon manganese oxide(Mn_(x)O_(y)) nanostructures, and/or carbon, e.g., frustules havingformed thereon carbon nanostructures, e.g., carbon nanotube (CNTs). Whenthe electrodes of opposite charge types are configured asymmetrically,the electrodes of different types of charge may include frustules havingdifferent ones of these nanostructures. Symmetric supercapacitors havingelectrodes of both charge types that include the same metal oxide onfrustules, e.g., Zn_(x)O_(y) or Mn_(x)O_(y) are predominantly pseudocapacitors. Symmetric supercapacitors having electrodes of both chargetypes that include carbon nanostructures on frustules, e.g., CNT, arepredominantly EDLCs. Asymmetric supercapacitors having an electrode offirst charge type that includes one of transition metal oxides and anelectrode of second charge type that includes CNT on frustules withouttransition metal oxides, e.g., first and second surface active materialsthat include Mn_(x)O_(y) and CNT, respectively, and Zn_(x)O_(y) and CNT,respectively, are hybrid capacitors that combine characteristics of botha pseudo capacitor on one electrode and an EDLC on the other electrode.

Supercapacitors can comprise a suitable commercially available separatoror a printed separator, e.g., a printed separator comprising frustulesand/or graphene oxide.

In some embodiments, supercapacitors comprise an ionic liquid thatserves as an electrolyte. In some embodiments, supercapacitors comprisea combination of an ionic liquid and one of both of a salt and a solventserving as an electrolyte. In some embodiments, the electrolyteessentially consists of an ionic liquid.

A current collector can comprise a suitable electrically conductingmaterial, e.g. Al, Cu, Ni, stainless steel, graphite/graphene/CNTs,foil, etc. The foils can be laminated with a polymer from one side. Acurrent collector can be formed from a printed conductive ink. The inkcan include Al, Ni, Ag, Cu, Bi, carbon, carbon nanotubes, graphene,graphite and other conductive metals and mixture of thereof.

Substrates on which different layers are printed can be conductive ornon-conductive. Advantageously, the various layers of thesupercapacitors disclosed herein can be printed on flexible substrateshaving flexibility comparable to, e.g., a cloth. The substrates caninclude graphite paper, graphene paper, polyester film, polyimide film,Al foil, Cu foil, stainless foil, carbon foam, polycarbonate film,paper, coated paper, plastic coated paper, fiber paper and/or cardboard,to name a few.

After printing the various layers, supercapacitors can be encapsulatedby lamination, e.g., by printing/depositing a protective layer, forexample.

The supercapacitors can be printed in any suitable shape.Supercapacitors can be printed such that they are electrically connectedin in parallel and/or electrically connected in series. Supercapacitorscan be printed such that they are electrically connected in paralleland/or series with printed batteries.

Advantageously, the overall thickness of supercapacitor can be madeextremely thin. The entire supercapacitor, including the substrate, canhave a thickness of 10-50 microns, 50-100 microns, 100-200 microns,200-300 microns, 300-400 microns, 400-500 microns, 500-600 microns,600-700 microns, 700-800 microns 800-900 microns, 900-1000 microns,1000-1200 microns, 1200-1400 microns, 1400-1600 microns, 1600-1800microns, 1800-2000 microns, or a thickness in a range defined by any ofthese values.

Supercapacitor Fabrication Method

Advantageously, using the inks described above, one or more or alllayers of the supercapacitor can be printed. The one or more layers orthe entire supercapacitor can be printed using any of the printingtechniques described herein. Example printing processes that can be usedto print the one or more layers include coating, rolling, spraying,layering, spin coating, lamination and/or affixing processes, forexample, screen printing, inkjet printing, electro-optical printing,electroink printing, photoresist and other resist printing, thermalprinting, laser jet printing, magnetic printing, pad printing,flexographic printing, hybrid offset lithography, gravure and otherintaglio printing, die slot deposition, among other suitable printingtechniques.

The inks for printing one or more layers of the supercapacitor can beprepared by mixing various ink components described above, using any ofthe ink mixing techniques described herein, including mixing with a stirbar, mixing with a magnetic stirrer, vortexing (using a vortex machine),shaking (using a shaker), planetary centrifugal mixing, by rotation,three roll milling, ball milling, sonication and mixing using mortar andpestle, to name a few.

One or more layers printed using inks described above, including theelectrodes and/or the separator, can be treated using various processesdescribed above, including drying/curing techniques including short waveinfrared (IR) radiation, medium wave IR-radiation, hot air conventionalovens, electron beam curing and near infrared radiation, among othertechniques. When cured using convectional and IR ovens, the layers aresubjected to a temperature range of 50-200° C., 75-175° C., 100-150° C.or any temperature in a range defined by any of these values, for aduration of 1 to 60 minutes, 2 to 40 minutes, 3-15 minutes, or anyduration in a range defined by any of these values.

The one or more layers printed using inks described above, including theelectrodes and/or the separators, can be cured/dried using near-infrared(NIR) light energy, using a suitable equipment configured to generatesuch light source. One example equipment that can be used is availablefrom Adphos Group. Using NIR light energy to dry/cure the printed layerscan advantageously include shorter drying times, e.g., by as much as anorder of magnitude shorter (e.g., in seconds rather than minutes) thandrying times employed using IR or conventional ovens. The inventors havediscovered that the NIR radiation penetrates deeper into the printedlayers printed more effectively and quickly, thereby removing solventsfrom the entire thickness of the printed layers more effectively andquickly. To facilitate even faster drying of the printed layers, whenNIR radiation is used, heat-absorbing particles can be included in theink for the printed layers, thereby further improving the efficiency ofthe drying process. In some printed layers, such as electrodes, surfaceactive materials such as CNTs, Mn_(x)O_(y) or Zn_(x)O_(y) as well asother electrically conductive carbon included in the printed electrodelayers can serve as heat-absorbing particles to facilitate drying of theprinted layers. In some printed layers, such as separators, thermallyconductive additives, graphene oxide (GO), may be added to serve asheat-absorbing particles to facilitate drying of the printed layers. Asdescribed herein, because the thermally conductive additive such as GOcan be a good electrical insulator, the separator advantageouslymaintains the electrically insulating characteristics, while serving asa heat absorbing material. The inventors have found, when included aspart of a printed layer such as a printed separator layer, GO may reducethe drying time by as much as one order of magnitude, e.g., from tens orminutes to tens of seconds. When NIR radiation is used, the layers canbe dried/cured for a duration of 1-60 sec., 1-45 sec., 1-30 sec. or fora duration in a range defined by any of these values, which issignificantly shorter than drying/curing times that maybe employed usingother light sources, e.g., IR light sources.

Experimental Performance of Supercapacitors

FIGS. 16A and 16B illustrate experimental measurements performed on asupercapacitor having symmetric printed electrodes, where each of theelectrodes having opposite polarities comprises frustules having formedthereon zinc oxide (Zn_(x)O_(y), e.g., ZnO) nanostructures, such thatthe supercapacitor is configured as a pseudo capacitor. FIG. 16Aillustrates a charge/discharge curve measured on a supercapacitor havingsquare electrodes (1.6 cm×1.6 cm). The capacitor was charged/dischargedat 1 mA, and the charge time was 500 sec. The measured capacitance wasabout 0.06F. The cut-off voltage for calculations was 1V. FIG. 16Billustrates a charge/discharge curve measured on a similar capacitor asthat illustrated in FIG. 16A, in which the supercapacitor wascharged/discharged at a higher current 10 mA. The cut-off voltage forcharging was 3V. The measured capacitance was about 0.04F. The cut-offvoltage for calculations was 1V.

FIGS. 17A-17D illustrate experimental measurements performed on asupercapacitor having symmetric printed electrodes, where each of theelectrodes having opposite polarities comprises frustules having formedthereon manganese oxide (Mn_(x)O_(y)) nanostructures, such that thesupercapacitor is configured as a pseudo capacitor. FIG. 17A illustratesa charge/discharge curve measured on a supercapacitor having squareelectrodes (1.6 cm×1.6 cm). The capacitor was charged/discharged at 2mA, and the charge time was 500 sec. The measured capacitance was about0.14F. The cut-off voltage for calculations was 1V.

FIG. 17B illustrates a charge/discharge curve measured on asupercapacitor having square electrodes (1.6 cm×1.6 cm). The capacitorwas charged at 40 mA for 3 sec. and discharged at 0.4 mA. The measuredaverage capacitance was about 0.06F. The cut-off voltage forcalculations was 1V. The capacitance value was observed to increase withcycling. While only a few cycles are shown, the capacitor wassuccessfully cycled 1000 times without degradation. As illustrated, thecapacitors were demonstrated to charge relatively quickly, which is anadvantageous property of supercapacitors over batteries, as describedabove.

FIG. 17C illustrates a discharge curve measured on a supercapacitorhaving square electrodes (1.6 cm×1.6 cm). The capacitor was charged at40 mA for 3 sec. and discharged at 0.4 mA. The measured averagecapacitance was about 0.055F. The cut-off voltage for calculations was1V. While only one cycle (330^(th) cycle) is shown for illustrativepurposes, the capacitor was successfully cycled more than 1000 timeswithout substantial deterioration.

FIG. 17D illustrates a discharge curve measured on a supercapacitorhaving square electrodes (1.6 cm×1.6 cm). The capacitor was charged at40 mA for 3 sec. and discharged at 0.4 mA. The measured averagecapacitance was about 0.061F. The cut-off voltage for calculations was1V. While only one cycle (1000^(th) cycle) is shown for illustrativepurposes, the capacitor was successfully cycled more than 1000 timeswithout substantial deterioration.

FIGS. 18A-18E illustrate experimental measurements performed on asupercapacitor having asymmetric printed electrodes, where one of theelectrodes having opposite polarities comprises frustules having formedthereon manganese oxide (Mn_(x)O_(y)) nanostructures, while the other ofthe electrodes comprises frustules having formed thereon CNT, such thatthe supercapacitor is configured as a hybrid supercapacitor. Thespecific capacitance (C_(sp)), which can be defined as the measuredcapacitance multiplied by the specific surface area, of 100-340F/g atspecific current of 0.01-1A/g was obtained based on the amount ofsurface active material.

FIG. 18A illustrates a discharge curve measured on a supercapacitorhaving square electrodes (2.54. cm×2.54 cm). The capacitor was chargedat a constant voltage of 2V for 30 minutes and discharged at 2 mA. Themeasured capacitance was about 2.21F. The cut-off voltage forcalculations was 1V.

FIG. 18B illustrates a discharge curve measured on a supercapacitorhaving square electrodes (2.54. cm×2.54 cm). The capacitor was chargedat a constant voltage of 2V for 30 minutes and discharged at 2 mA. Themeasured capacitance was about 3.26F. The cut-off voltage forcalculations was 1V.

FIG. 18C illustrates a discharge curve measured on a supercapacitorhaving square electrodes (2.54. cm×2.54 cm). The capacitor was chargedat constant voltage of 3V for 30 minutes and discharged at 2 mA. Themeasured capacitance was about 3.86F. The cut-off voltage forcalculations was 1V.

FIG. 18D illustrates a charge/discharge curve measured on asupercapacitor having square electrodes (2.54. cm×2.54 cm). Thecapacitor was charged at 0.1A for 2 sec. and discharged at 1 mA. Themeasured capacitance was about 1.36F. The cut-off voltage forcalculations was 1V. As illustrated, the capacitor charged relativelyquickly, which is an advantageous property of supercapacitors overbatteries, as described above.

FIG. 18E illustrates a charge/discharge curve measured on asupercapacitor having square electrodes (2.54. cm×2.54 cm). Thecapacitor was charged to 4.5V at 2 mA for 2 sec. and discharged at 1 mA.The cut-off voltage for calculations was 2V. As illustrated, thecapacitors charged relatively quickly, which is an advantageous propertyof supercapacitors over batteries, as described above.

FIGS. 19A-19B illustrate experimental measurements performed on asupercapacitor having symmetric printed electrodes, where each of theelectrodes having opposite polarities comprises frustules having formedthereon CNT, such that the supercapacitor is configured as a doublelayer supercapacitor. The specific capacitance (C_(sp)) was 50-100F/g atspecific current of 0.01-1A/g based on the amount of surface activematerial.

FIG. 19A illustrates a charge/discharge curve measured on asupercapacitor having square electrodes (1.6 cm×1.6 cm). The capacitorwas charged at 1 mA for 500 sec. and discharged at 1 mA. The measuredcapacitance was about 0.08F. The cut-off voltage for calculations was1V.

FIG. 19B illustrates a discharge curve measured on a supercapacitorhaving square electrodes (2.54. cm×2.54 cm). The capacitor was chargedto 3V at 5 mA and discharged at 5 mA. The measured capacitance was about0.06F. The cut-off voltage for calculations was 1V.

EXAMPLE EMBODIMENTS

The following example embodiments identify some possible permutations ofcombinations of features disclosed herein, although other permutationsof combinations of features are also possible.

1. A printed energy storage device comprising:

-   -   a first electrode;    -   a second electrode; and    -   a separator between the first electrode and the second        electrode, at least one of the first electrode, the second        electrode, and the separator including frustules.

2. The device of Embodiment 1, wherein the separator includes thefrustules.

3. The device of Embodiment 1 or 2, wherein the first electrode includesthe frustules.

4. The device of any of Embodiments 1-3, wherein the second electrodeincludes the frustules.

5. The device of any one of Embodiments 1-4, wherein the frustules havea substantially uniform property.

6. The device of Embodiment 5, wherein property comprises shape.

7. The device of Embodiment 6, wherein the shape comprises a cylinder, asphere, a disc, or a prism.

8. The device of any of Embodiments 5-7, wherein the property comprisesa dimension.

9. The device of Embodiment 8, wherein the dimension comprises diameter.

10. The device of Embodiment 9, wherein the diameter is in a range fromabout 2 μm to about 10 μm.

11. The device of Embodiment 8, wherein the dimension comprises length.

12. The device of Embodiment 9, wherein the length is in a range fromabout 5 μm to about 20 μm.

13. The device of Embodiment 8, wherein the dimension comprises alongest axis.

14. The device of Embodiment 9, wherein the longest axis is in a rangefrom about 5 μm to about 20 μm.

15. The device of any of Embodiments 5-14, wherein the propertycomprises porosity.

16. The device of Embodiment 15, wherein the porosity is in a range fromabout 20% to about 50%.

17. The device of any of Embodiments 5-16, wherein the propertycomprises mechanical strength.

18. The device of any of Embodiment 1-17, wherein the frustules comprisea surface modifying structure.

19. The device of Embodiment 18, wherein the surface modifying structureincludes a conductive material.

20. The device of Embodiment 19, wherein the conductive materialincludes at least one of silver, aluminum, tantalum, copper, lithium,magnesium, and brass.

21. The device of any of Embodiments 18-20, wherein the surfacemodifying structure includes zinc oxide (ZnO).

22. The device of any of Embodiments 18-21, wherein the surfacemodifying structure includes a semiconductor.

23. The device of Embodiment 22, wherein the semiconductor includes atleast one of silicon, germanium, silicon germanium, and galliumarsenide.

24. The device of any of Embodiments 18-23, wherein the surfacemodifying structure comprises at least one of a nanowire, ananoparticle, and a structure having a rosette shape.

25. The device of any of Embodiments 18-24, wherein the surfacemodifying structure is on an exterior surface of the frustules.

26. The device of any of Embodiments 18-25, wherein the surfacemodifying structure is on an interior surface of the frustules.

27. The device of any of Embodiments 1-26, wherein the frustulescomprise a surface modifying material.

28. The device of Embodiment 27, wherein the surface modifying materialincludes a conductive material.

29. The device of Embodiment 28, wherein the conductive materialincludes at least one of silver, aluminum, tantalum, copper, lithium,magnesium, and brass.

30. The device of any of Embodiments 27-29, wherein the surfacemodifying material includes zinc oxide (ZnO).

31. The device of any of Embodiments 27-30, wherein the surfacemodifying material includes a semiconductor.

32. The device of Embodiment 31, wherein the semiconductor includes atleast one of silicon, germanium, silicon germanium, and galliumarsenide.

33. The device of any of Embodiments 27-32, wherein the surfacemodifying material is on an exterior surface of the frustules.

34. The device of any of Embodiments 37-33, wherein the surfacemodifying material is on an interior surface of the frustules.

35. The device of any of Embodiments 1-34, wherein the first electrodecomprises a conductive filler.

36. The device of any of Embodiments 1-35, wherein the second electrodecomprises a conductive filler.

37. The device of Embodiment 34 or 35, wherein the conductive fillercomprises graphitic carbon.

38. The device of any of Embodiments 35-37, wherein the conductivefiller comprises graphene.

39. The device of any of Embodiments 1-38, wherein the first electrodecomprises an adherence material.

40. The device of any of Embodiments 1-39, wherein the second electrodecomprises an adherence material.

41. The device of any of Embodiments 1-40, wherein the separatorcomprises an adherence material.

42. The device of any of Embodiments 39-41, wherein the adherencematerial comprises a polymer.

43. The device of any of Embodiments 1-42, wherein the separatorcomprises an electrolyte.

44. The device of Embodiment 43, wherein the electrolyte comprises atleast one of an ionic liquid, an acid, a base, and a salt.

45. The device of Embodiment 43 or 44, wherein the electrolyte comprisesan electrolytic gel.

46. The device of any of Embodiments 1-45, further comprising a firstcurrent collector in electrical communication with the first electrode.

47. The device of any of Embodiments 1-46, further comprising a secondcurrent collector in electrical communication with the second electrode.

48. The device of any of Embodiments 1-47, wherein the printed energystorage device comprises a capacitor.

49. The device of any of Embodiments 1-47, wherein the printed energystorage device comprises a supercapacitor.

50. The device of any of Embodiments 1-47, wherein the printed energystorage device comprises a battery.

51. A system comprising a plurality of the devices of any of Embodiments1-50 stacked on top of each other.

52. An electrical device comprising the device of any of Embodiments1-50 or the system of Embodiment 51.

53. A membrane for a printed energy storage device, the membranecomprising frustules.

54. The membrane of Embodiment 53, wherein the frustules have asubstantially uniform property.

55. The membrane of Embodiment 54, wherein the property comprises shape.

56. The membrane of Embodiment 55, wherein the shape comprises acylinder, a sphere, a disc, or a prism.

57. The membrane of any of Embodiments 54-56, wherein the propertycomprises a dimension.

58. The membrane of Embodiment 57, wherein the dimension comprisesdiameter.

59. The membrane of Embodiment 58, wherein the diameter is in a rangefrom about 2 μm to about 10 μm.

60. The membrane of any of Embodiments 54-59, wherein the dimensioncomprises length.

61. The membrane of Embodiment 60, wherein the length is in a range ofabout 5 iim to about 20 μm.

62. The membrane of any of Embodiments 54-61, wherein the dimensioncomprises a longest axis.

63. The membrane of Embodiment 62, wherein the longest axis is in arange of about 5 μm to about 20 μm.

64. The membrane of any of Embodiments 54-63, wherein the propertycomprises porosity.

65. The membrane of Embodiment 64, wherein the porosity is in a rangefrom about 20% to about 50%.

66. The membrane of any of Embodiments 54-65, wherein the propertycomprises mechanical strength.

67. The membrane of any of Embodiments 53-66, wherein the frustulescomprise a surface modifying structure.

68. The membrane of Embodiment 67, wherein the surface modifyingstructure includes a conductive material.

69. The membrane of Embodiment 68, wherein the conductive materialincludes at least one of silver, aluminum, tantalum, copper, lithium,magnesium, and brass.

70. The membrane of any of Embodiments 67-69, wherein the surfacemodifying structure includes zinc oxide (ZnO).

71. The membrane of any of Embodiments 67-70, wherein the surfacemodifying structure includes a semiconductor.

72. The membrane of Embodiment 71, wherein the semiconductor includes atleast one of silicon, germanium, silicon germanium, and galliumarsenide.

73. The membrane of any of Embodiments 67-72, wherein the surfacemodifying structure comprises at least one of a nanowire, ananoparticle, and a structure having a rosette shape.

74. The membrane of any of Embodiments 67-73, wherein the surfacemodifying structure is on an exterior surface of the frustules.

75. The membrane of any of Embodiments 67-74, wherein the surfacemodifying structure is on an interior surface of the frustules.

76. The membrane of any of Embodiments 53-75, wherein the frustulescomprises a surface modifying material.

77. The membrane of Embodiment 76, wherein surface modifying materialincludes a conductive material.

78. The membrane of Embodiment 77, wherein the conductive materialincludes at least one of silver, aluminum, tantalum, copper, lithium,magnesium, and brass.

79. The membrane of any of Embodiments 76-78, wherein the surfacemodifying material includes zinc oxide (ZnO).

80. The membrane of any of Embodiments 76-79, wherein the surfacemodifying material includes a semiconductor.

81. The membrane of Embodiment 80, wherein the semiconductor includes atleast one of silicon, germanium, silicon germanium, and galliumarsenide.

82. The membrane of any of Embodiments 76-81, wherein the surfacemodifying material is on an exterior surface of the frustules.

83. The membrane of any of Embodiments 76-82, wherein the surfacemodifying material is on an interior surface of the frustules.

84. The membrane of any of Embodiments 83-83, further comprising aconductive filler.

85. The membrane of Embodiment 84, wherein the conductive fillercomprises graphitic carbon.

86. The membrane of Embodiment 84 or 85, wherein the conductive fillercomprises graphene.

87. The membrane of any of Embodiments 53-86, further comprising anadherence material.

88. The membrane of Embodiment 87, wherein the adherence materialcomprises a polymer.

89. The membrane of any of Embodiments 53-88, further comprising anelectrolyte.

90. The membrane of Embodiment 89, wherein the electrolyte comprises atleast one of an ionic liquid, an acid, a base, and a salt.

91. The membrane of Embodiment 89 or 90, wherein the electrolytecomprises an electrolytic gel.

92. An energy storage device comprising the membrane of any ofEmbodiments 53-91.

93. The device of Embodiment 92, wherein the printed energy storagedevice comprises a capacitor.

94. The device of Embodiment 92, wherein the printed energy storagedevice comprises a supercapacitor.

95. The device of Embodiment 92, wherein the printed energy storagedevice comprises a battery.

96. A system comprising a plurality of the devices of any of Embodiments92-95 stacked on top of each other.

97. An electrical device comprising the device of any of Embodiments92-95 or the system of Embodiment 96.

98. A method of manufacturing a printed energy storage device, themethod comprising:

-   -   forming a first electrode;    -   forming a second electrode; and    -   forming a separator between the first electrode and the second        electrode, at least one of the first electrode, the second        electrode, and the separator including frustules.

99. The method of Embodiment 98, wherein the separator includes thefrustules.

100. The method of Embodiment 99, wherein forming the separator includesforming a dispersion including the frustules.

101. The method of Embodiment 99 or 100, wherein forming the separatorincludes screen printing the separator.

102. The method of Embodiment 99, wherein forming the separator includesforming a membrane including the frustules.

103. The method of Embodiment 102, wherein forming the separatorincludes roll-to-roll printing the membrane including the separator.

104. The method of any of Embodiments 98-103, wherein the firstelectrode includes the frustules.

105. The method of Embodiment 104, wherein forming the first electrodeincludes forming a dispersion including the frustules.

106. The method of Embodiment 104 or 105, wherein forming the firstelectrode includes screen printing the first electrode.

107. The method of Embodiment 104, wherein forming the first electrodeincludes forming a membrane including the frustules.

108. The method of Embodiment 107, wherein forming the first electrodeincludes roll-to-roll printing the membrane including the firstelectrode.

109. The method of any of Embodiments 98-108, wherein the secondelectrode includes the frustules.

110. The method of Embodiment 109, wherein forming the second electrodeincludes forming a dispersion including the frustules.

111. The method of Embodiment 109 or 110, wherein forming the secondelectrode includes screen printing the second electrode.

112. The method of Embodiment 109, wherein forming the second electrodeincludes forming a membrane including the frustules.

113. The method of Embodiment 112, wherein forming the second electrodeincludes roll-to-roll printing the membrane including the secondelectrode.

114. The method of any of Embodiments 98-113, further comprising sortingthe frustules according to a property.

115. The method of Embodiment 114, wherein the property comprises atleast one of shape, dimension, material, and porosity.

116. An ink comprising:

-   -   a solution; and    -   frustules dispersed in the solution.

117. The ink of Embodiment 116, wherein the frustules have asubstantially uniform property.

118. The ink of Embodiment 117, wherein the property comprises shape.

119. The ink of Embodiment 118, wherein the shape comprises a cylinder,a sphere, a disc, or a prism.

120. The ink of any of Embodiments 117-119, wherein the propertycomprises a dimension.

121. The ink of Embodiment 120, wherein the dimension comprisesdiameter. 122. The ink of Embodiment 121, wherein the diameter is in arange from about 2 μm to about 10 μm.

123. The ink of any of Embodiments 117-122, wherein the dimensioncomprises length.

124. The ink of Embodiment 123, wherein the length is in a range ofabout 5 μm to about 20

125. The ink of any of Embodiments 117-124, wherein the dimensioncomprises a longest axis.

126. The ink of Embodiment 125, wherein the longest axis is in a rangeof about 5 to about 20

127. The ink of any of Embodiments 117-126, wherein the propertycomprises porosity.

128. The ink of Embodiment 127, wherein the porosity is in a range fromabout 20% to about 50%.

129. The ink of any of Embodiments 117-128, wherein the propertycomprises mechanical strength.

130. The ink of any of Embodiments 116-129, wherein the frustulescomprise a surface modifying structure.

131. The ink of Embodiment 130, wherein the surface modifying structureincludes a conductive material.

132. The ink of Embodiment 131, wherein the conductive material includesat least one of silver, aluminum, tantalum, copper, lithium, magnesium,and brass.

133. The ink of any of Embodiments 130-132, wherein the surfacemodifying structure includes zinc oxide (ZnO).

134. The ink of any of Embodiments 130-133, wherein the surfacemodifying structure includes a semiconductor.

135. The ink of Embodiment 134, wherein the semiconductor includes atleast one of silicon, germanium, silicon germanium, and galliumarsenide.

136. The ink of any of Embodiments 130-135, wherein the surfacemodifying structure comprises at least one of a nanowire, ananoparticle, and a structure having a rosette shape.

137. The ink of any of Embodiments 130-136, wherein the surfacemodifying structure is on an exterior surface of the frustules.

138. The ink of any of Embodiments 130-137, wherein the surfacemodifying structure is on an interior surface of the frustules.

139. The ink of any of Embodiments 116-138, wherein the frustulescomprises a surface modifying material.

140. The ink of Embodiment 139, wherein surface modifying materialincludes a conductive material.

141. The ink of Embodiment 140, wherein the conductive material includesat least one of silver, aluminum, tantalum, copper, lithium, magnesium,and brass.

142. The ink of any of Embodiments 139-141, wherein the surfacemodifying material includes zinc oxide (ZnO).

143. The ink of any of Embodiments 139-142, wherein the surfacemodifying material includes a semiconductor.

144. The ink of Embodiment 143, wherein the semiconductor includes atleast one of silicon, germanium, silicon germanium, and galliumarsenide.

145. The ink of any of Embodiments 139-144, wherein the surfacemodifying material is on an exterior surface of the frustules.

146. The ink of any of Embodiments 139-145, wherein the surfacemodifying material is on an interior surface of the frustules.

147. The ink of any of Embodiments 116-146, further comprising aconductive filler.

148. The ink of Embodiment 147, wherein the conductive filler comprisesgraphitic carbon.

149. The ink of Embodiment 147 or 148, wherein the conductive fillercomprises graphene.

150. The ink of any of Embodiments 116-149, further comprising anadherence material.

151. The ink of Embodiment 150, wherein the adherence material comprisesa polymer.

152. The ink of any of Embodiments 116-151, further comprising anelectrolyte.

153. The ink of Embodiment 152, wherein the electrolyte comprises atleast one of an ionic liquid, an acid, a base, and a salt.

154. The ink of Embodiment 152 or 153, wherein the electrolyte comprisesan electrolytic gel.

155. A device comprising the ink of any of Embodiments 116-154.

156. The device of Embodiment 155, wherein the device comprises aprinted energy storage device.

157. The device of Embodiment 156, wherein the printed energy storagedevice comprises a capacitor.

158. The device of Embodiment 156, wherein the printed energy storagedevice comprises a supercapacitor.

159. The device of Embodiment 156, wherein the printed energy storagedevice comprises a battery.

160. A method of extracting a diatom frustule portion, the methodcomprising:

-   -   dispersing a plurality of diatom frustule portions in a        dispersing solvent;    -   removing at least one of an organic contaminant and an inorganic        contaminant;    -   dispersing the plurality of diatom frustule portions in a        surfactant, the surfactant reducing an agglomeration of the        plurality of diatom frustule portions; and    -   extracting a plurality of diatom frustule portions having at        least one common characteristic using a disc stack centrifuge.

161. The method of embodiment 160, wherein the at least one commoncharacteristic comprises at least one of a dimension, a shape, amaterial, and a degree of brokenness.

162. The method of embodiment 161, wherein the dimension comprises atleast one of a length and a diameter.

163. The method of any one of embodiments 160 to 162, wherein a solidmixture comprises the plurality of diatom frustule portions.

164. The method of embodiment 163, further comprising reducing aparticle dimension of the solid mixture.

165. The method of embodiment 164, wherein reducing the particledimension of the solid mixture is before dispersing the plurality ofdiatom frustule portions in the dispersing solvent.

166. The method of embodiment 164 or 165, wherein reducing the particledimension comprises grinding the solid mixture.

167. The method of embodiment 166, wherein grinding the solid mixturecomprises applying to the solid mixture at least one of a mortar and apestle, a jar mill, and a rock crusher.

168. The method of any one of embodiments 163 to 167, further comprisingextracting a component of the solid mixture having a longest componentdimension that is greater than a longest frustule portion dimension ofthe plurality of diatom frustule portions.

169. The method of embodiment 168, wherein extracting the component ofthe solid mixture comprises sieving the solid mixture.

170. The method of embodiment 169, wherein sieving the solid mixturecomprises processing the solid mixture with a sieve having a mesh sizefrom about 15 microns to about 25 microns.

171. The method of embodiment 169, wherein sieving the solid mixturecomprises processing the solid mixture with a sieve having a mesh sizefrom about 10 microns to about 25 microns.

172. The method of any one of embodiments 160 to 171, further comprisingsorting the plurality of diatom frustule portions to separate a firstdiatom frustule portion from a second diatom frustule portion, the firstdiatom frustule portion having a greater longest dimension.

173. The method of embodiment 172, wherein the first diatom frustuleportion comprises a plurality of unbroken diatom frustule portions.

174. The method of embodiment 172 or 173, wherein the second diatomfrustule portion comprises a plurality of broken diatom frustuleportions.

175. The method of any one of embodiments 172 to 174, wherein sortingcomprises filtering the plurality of diatom frustule portions.

176. The method of embodiment 175, wherein filtering comprisesdisturbing agglomeration of the plurality of diatom frustule portions.

177. The method of embodiment 176, wherein disturbing agglomeration ofthe plurality of diatom frustule portions comprises stirring.

178. The method of embodiment 176 or 177, wherein disturbingagglomeration of the plurality of diatom frustule portions comprisesshaking.

179. The method of any one of embodiments 176 to 178, wherein disturbingagglomeration of the plurality of diatom frustule portions comprisesbubbling.

180. The method of any one of embodiments 175 to 179, wherein filteringcomprises applying a sieve to the plurality of diatom frustule portions.

181. The method of embodiment 180, wherein the sieve has a mesh sizefrom about 5 microns to about 10 microns.

182. The method of embodiment 180, wherein the sieve has a mesh size ofabout 7 microns.

183. The method of any one of embodiments 160 to 182, further comprisingobtaining a washed diatom frustule portion.

184. The method of embodiment 183, wherein obtaining the washed diatomfrustule portion comprises washing the plurality of diatom frustuleportions with a cleaning solvent after removing the at least one of theorganic contaminant and the inorganic contaminant.

185. The method of embodiment 183 or 184, wherein obtaining the washeddiatom frustule portion comprises washing the diatom frustule portionhaving the at least one common characteristic with a cleaning solvent.

186. The method of embodiment 184 or 185, further comprising removingthe cleaning solvent.

187. The method of embodiment 186, wherein removing the cleaning solventcomprises sedimenting the plurality of diatom frustule portions afterremoving at least one of the organic contaminant and the inorganiccontaminant.

188. The method of embodiment 186 or 187, wherein removing the cleaningsolvent comprises sedimenting the plurality of diatom frustule portionshaving the at least one common characteristic.

189. The method of embodiment 187 or 188, wherein sedimenting comprisescentrifuging.

190. The method of embodiment 189, wherein centrifuging comprisesapplying a centrifuge suitable for large scale processing.

191. The method of embodiment 190, wherein centrifuging comprisesapplying at least one of a disc stack centrifuge, a decanter centrifuge,and a tubular bowl centrifuge.

192. The method of any one of embodiments 184 to 191, wherein at leastone of the dispersing solvent and the cleaning solvent comprises water.

193. The method of any one of embodiments 160 to 192, wherein at leastone of dispersing the plurality of diatom frustule portions in thedispersing solvent and dispersing the plurality of diatom frustuleportions in the surfactant comprises sonicating the plurality of diatomfrustules.

194. The method of any one of embodiments 160 to 193, wherein thesurfactant comprises a cationic surfactant.

195. The method of embodiment 194, wherein the cationic surfactantcomprises at least one of a benzalkonium chloride, a cetrimoniumbromide, a lauryl methyl gluceth-10 hydroxypropyl dimonium chloride, abenzethonium chloride, a benzethonium chloride, a bronidox, admethyldioctadecylammonium chloride, and a tetramethylammoniumhydroxide.

196. The method of any one of embodiments 160 to 195, wherein thesurfactant comprises a non-ionic surfactant.

197. The method of embodiment 196, wherein the non-ionic surfactantcomprises at least one of a cetyl alcohol, a stearyl alcohol, acetostearyl alcohol, an oleyl alcohol, a polyoxyethylene glycol alkylether, an octaethylene glycol monododecyl ether, a glucoside alkylethers, a decyl glucoside, a polyoxyethylene glycol octylphenol ethers,an octylphenol ethoxylate (Triton X-100™), a nonoxynol-9, a glyceryllaurate, a polysorbate, and a poloxamer.

198. The method of any one of embodiments 160 to 197, further comprisingdispersing the plurality of diatom frustules in an additive component.

199. The method of embodiment 198, wherein dispersing the plurality ofdiatom frustules in an additive component is before dispersing theplurality of diatom frustules in the surfactant.

200. The method of embodiment 198, wherein dispersing the plurality ofdiatom frustules in an additive component is after dispersing theplurality of diatom frustules in the surfactant.

201. The method of embodiment 198, wherein dispersing the plurality ofdiatom frustules in an additive component is at least partiallysimultaneous with dispersing the plurality of diatom frustules in thesurfactant.

202. The method of any one of embodiments 198 to 201, wherein theadditive component comprises at least one of a potassium chloride, anammonium chloride, an ammonium hydroxide, and a sodium hydroxide.

203. The method of any one of embodiments 160 to 202, wherein dispersingthe plurality of diatom frustule portions comprises obtaining adispersion comprising about 1 weight percent to about 5 weight percentof the plurality of diatom frustule portions.

204. The method of any one of embodiments 160 to 203, wherein removingthe organic contaminant comprises heating the plurality of diatomfrustule portions in the presence of a bleach.

205. The method of embodiment 204, wherein the bleach comprises at leastone of a hydrogen peroxide and a nitric acid.

206. The method of embodiment 205, wherein heating comprises heating theplurality of diatom frustule portions in a solution comprising an amountof hydrogen peroxide in a range from about 10 volume percent to about 20volume percent.

207. The method of any one of embodiments 204 to 206, wherein heatingcomprises heating the plurality of diatom frustule portions for aduration of about 5 minutes to about 15 minutes.

208. The method of any one of embodiments 160 to 207, wherein removingthe organic contaminant comprises annealing the plurality of diatomfrustule portions.

209. The method of any one of embodiments 160 to 208, wherein removingthe inorganic contaminant comprises combining the plurality of diatomfrustule portions with at least one of a hydrochloric acid and asulfuric acid.

210. The method of embodiment 209, wherein the combining comprisesmixing the plurality of diatom frustule portions in a solutioncomprising about 15 volume percent to about 25 volume percent ofhydrochloric acid.

211. The method of embodiment 210, wherein the mixing is for a durationof about 20 minutes to about 40 minutes.

212. A method of extracting a diatom frustule portion, the methodcomprising:

-   -   extracting a plurality of diatom frustule portions having at        least one common characteristic using a disc stack centrifuge.

213. The method of embodiment 212, further comprising dispersing theplurality of diatom frustule portions in a dispersing solvent.

214. The method of embodiment 212 or 213, further comprising removing atleast one of an organic contaminant and an inorganic contaminant.

215. The method of any one of embodiments 212 to 214, further comprisingdispersing the plurality of diatom frustule portions in a surfactant,the surfactant reducing an agglomeration of the plurality of diatomfrustule portions.

216. The method of any one of embodiments 212 to 215, wherein the atleast one common characteristic comprises at least one of a dimension, ashape, a material, and a degree of brokenness.

217. The method of embodiment 216, wherein the dimension comprises atleast one of a length and a diameter.

218. The method of any one of embodiments 212 to 217, wherein a solidmixture comprises the plurality of diatom frustule portions.

219. The method of embodiment 218, further comprising reducing aparticle dimension of the solid mixture.

220. The method of embodiment 219, wherein reducing the particledimension of the solid mixture is before dispersing the plurality ofdiatom frustule portions in the dispersing solvent.

221. The method of embodiment 219 or 220, wherein reducing the particledimension comprises grinding the solid mixture.

222. The method of embodiment 221, wherein grinding the solid mixturecomprises applying to the solid mixture at least one of a mortar and apestle, a jar mill, and a rock crusher.

223. The method of any one of embodiments 219 to 222, further comprisingextracting a component of the solid mixture having a longest componentdimension that is greater than a longest frustule portion dimension ofthe plurality of diatom frustule portions.

224. The method of embodiment 223, wherein extracting the component ofthe solid mixture comprises sieving the solid mixture.

225. The method of embodiment 224, wherein sieving the solid mixturecomprises processing the solid mixture with a sieve having a mesh sizefrom about 15 microns to about 25 microns.

226. The method of embodiment 224, wherein sieving the solid mixturecomprises processing the solid mixture with a sieve having a mesh sizefrom about 10 microns to about 25 microns.

227. The method of any one of embodiments 212 to 226, further comprisingsorting the plurality of diatom frustule portions to separate a firstdiatom frustule portion from a second diatom frustule portion, the firstdiatom frustule portion having a greater longest dimension.

228. The method of embodiment 227, wherein the first diatom frustuleportion comprises a plurality of unbroken diatom frustule portions.

229. The method of embodiment 227 or 228, wherein the second diatomfrustule portion comprises a plurality of broken diatom frustuleportions.

230. The method of any one of embodiments 227 to 229, wherein sortingcomprises filtering the plurality of diatom frustule portions.

231. The method of embodiment 230, wherein filtering comprisesdisturbing agglomeration of the plurality of diatom frustule portions.

232. The method of embodiment 231, wherein disturbing agglomeration ofthe plurality of diatom frustule portions comprises stirring.

233. The method of embodiment 231 or 282, wherein disturbingagglomeration of the plurality of diatom frustule portions comprisesshaking.

234. The method of any one of embodiments 231 to 233, wherein disturbingagglomeration of the plurality of diatom frustule portions comprisesbubbling.

235. The method of any one of embodiments 230 to 234, wherein filteringcomprises applying a sieve to the plurality of diatom frustule portions.

236. The method of embodiment 235, wherein the sieve has a mesh sizefrom about 5 microns to about 10 microns.

237. The method of embodiment 235, wherein the sieve has a mesh size ofabout 7 microns.

238. The method of any one of embodiments 212 to 237, further comprisingobtaining a washed diatom frustule portion.

239. The method of embodiment 238, wherein obtaining the washed diatomfrustule portion comprises washing the plurality of diatom frustuleportions with a cleaning solvent after removing at least one of theorganic contaminant and the inorganic contaminant.

240. The method of embodiment 238 or 239, wherein obtaining the washeddiatom frustule portion comprises washing the diatom frustule portionhaving the at least one common characteristic with a cleaning solvent.

241. The method of embodiment 239 or 240, further comprising removingthe cleaning solvent.

242. The method of embodiment 241, wherein removing the cleaning solventcomprises sedimenting the plurality of diatom frustule portions afterremoving the at least one of the organic contaminant and the inorganiccontaminant.

243. The method of embodiment 241 or 242, wherein removing the cleaningsolvent comprises sedimenting the plurality of diatom frustule portionshaving the at least one common characteristic.

244. The method of embodiment 242 or 243, wherein sedimenting comprisescentrifuging.

245. The method of embodiment 244, wherein centrifuging comprisesapplying a centrifuge suitable for large scale processing.

246. The method of embodiment 245, wherein centrifuging comprisesapplying at least one of a disc stack centrifuge, a decanter centrifuge,and a tubular bowl centrifuge.

247. The method of any one of embodiments 240 to 246, wherein at leastone of the dispersing solvent and the cleaning solvent comprises water.

248. The method of any one of embodiments 215 to 247, wherein at leastone of dispersing the plurality of diatom frustule portions in thedispersing solvent and dispersing the plurality of diatom frustuleportions in the surfactant comprises sonicating the plurality of diatomfrustules.

249. The method of any one of embodiments 215 to 248, wherein thesurfactant comprises a cationic surfactant.

250. The method of embodiment 249, wherein the cationic surfactantcomprises at least one of a benzalkonium chloride, a cetrimoniumbromide, a lauryl methyl gluceth-10 hydroxypropyl dimonium chloride, abenzethonium chloride, a benzethonium chloride, a bronidox, admethyldioctadecylammonium chloride, and a tetramethylammoniumhydroxide.

251. The method of any one of embodiments 212 to 250, wherein thesurfactant comprises a non-ionic surfactant.

252. The method of embodiment 251, wherein the non-ionic surfactantcomprises at least one of a cetyl alcohol, a stearyl alcohol, acetostearyl alcohol, an oleyl alcohol, a polyoxyethylene glycol alkylether, an octaethylene glycol monododecyl ether, a gluco side alkylethers, a decyl glucoside, a polyoxyethylene glycol octylphenol ethers,an octylphenol ethoxylate (Triton X-100™), a nonoxynol-9, a glyceryllaurate, a polysorbate, and a poloxamer.

253. The method of any one of embodiments 212 to 252, further comprisingdispersing the plurality of diatom frustules in an additive component.

254. The method of embodiment 253, wherein dispersing the plurality ofdiatom frustules in an additive component is before dispersing theplurality of diatom frustules in the surfactant.

255. The method of embodiment 253, wherein dispersing the plurality ofdiatom frustules in an additive component is after dispersing theplurality of diatom frustules in the surfactant.

256. The method of embodiment 253, wherein dispersing the plurality ofdiatom frustules in an additive component is at least partiallysimultaneous with dispersing the plurality of diatom frustules in thesurfactant.

257. The method of any one of embodiments 253 to 256, wherein theadditive component comprises at least one of a potassium chloride, anammonium chloride, an ammonium hydroxide, and a sodium hydroxide.

258. The method of any one of embodiments 213 to 257, wherein dispersingthe plurality of diatom frustule portions in the dispersing solventcomprises obtaining a dispersion comprising about 1 weight percent toabout 5 weight percent of the plurality of diatom frustule portions.

259. The method of any one of embodiments 214 to 258, wherein removingthe organic contaminant comprises heating the plurality of diatomfrustule portions in the presence of a bleach.

260. The method of embodiment 259, wherein the bleach comprises at leastone of a hydrogen peroxide, and a nitric acid.

261. The method of embodiment 260, wherein heating comprises heating theplurality of diatom frustule portions in a solution comprising an amountof hydrogen peroxide in a range from about 10 volume percent to about 20volume percent.

262. The method of any one of embodiments 259 to 261, wherein heatingcomprises heating the plurality of diatom frustule portions for aduration of about 5 minutes to about 15 minutes.

263. The method of any one of embodiments 214 to 262, wherein removingthe organic contaminant comprises annealing the plurality of diatomfrustule portions.

264. The method of any one of embodiments 214 to 263, wherein removingthe inorganic contaminant comprises combining the plurality of diatomfrustule portions with at least one of a hydrochloric acid and asulfuric acid.

265. The method of embodiment 264, wherein combining comprises mixingthe plurality of diatom frustule portions in a solution comprising about15 volume percent to about 25 volume percent of hydrochloric acid.

266. The method of embodiment 265, wherein the mixing is for a durationof about 20 minutes to about 40 minutes.

267. A method of extracting a diatom frustule portion, the methodcomprising:

-   -   dispersing a plurality of diatom frustule portions with a        surfactant, the surfactant reducing an agglomeration of the        plurality of diatom frustule portions.

268. The method of embodiment 267, further comprising extracting aplurality of diatom frustule portions having at least one commoncharacteristic using a disc stack centrifuge.

269. The method of embodiment 267 or 268, further comprising dispersingthe plurality of diatom frustule portions in a dispersing solvent.

270. The method of any one of embodiments 267 to 269, further comprisingremoving at least one of an organic contaminant and an inorganiccontaminant.

271. The method of any one of embodiments 267 to 270, wherein the atleast one common characteristic comprises at least one of a dimension, ashape, a material, and a degree of brokenness.

272. The method of embodiment 271, wherein the dimension comprises atleast one of a length and a diameter.

273. The method of any one of embodiments 267 to 272, wherein a solidmixture comprises the plurality of diatom frustule portions.

274. The method of embodiment 273, further comprising reducing aparticle dimension of the solid mixture.

275. The method of embodiment 274, wherein reducing the particledimension of the solid mixture is before dispersing the plurality ofdiatom frustule portions in the dispersing solvent.

276. The method of embodiment 274 or 275, wherein reducing the particledimension comprises grinding the solid mixture.

277. The method of embodiment 276, wherein grinding the solid mixturecomprises applying to the solid mixture at least one of a mortar and apestle, a jar mill, and a rock crusher.

278. The method of any one of embodiments 273 to 277, further comprisingextracting a component of the solid mixture having a longest componentdimension that is greater than a longest frustule portion dimension ofthe plurality of diatom frustule portions.

279. The method of embodiment 278, wherein extracting the component ofthe solid mixture comprises sieving the solid mixture.

280. The method of embodiment 279, wherein sieving the solid mixturecomprises processing the solid mixture with a sieve having a mesh sizefrom about 15 microns to about 25 microns.

281. The method of embodiment 279, wherein sieving the solid mixturecomprises processing the solid mixture with a sieve having a mesh sizefrom about 10 microns to about 25 microns.

282. The method of any one of embodiments 267 to 281, further comprisingsorting the plurality of diatom frustule portions to separate a firstdiatom frustule portion from a second diatom frustule portion, the firstdiatom frustule portion having a greater longest dimension.

283. The method of embodiment 282, wherein the first diatom frustuleportion comprises a plurality of unbroken diatom frustule portions.

284. The method of embodiment 282 or 283, wherein the second diatomfrustule portion comprises a plurality of broken diatom frustuleportions.

285. The method of any one of embodiments 282 to 284, wherein sortingcomprises filtering the plurality of diatom frustule portions.

286. The method of embodiment 285, wherein filtering comprisesdisturbing agglomeration of the plurality of diatom frustule portions.

287. The method of embodiment 286, wherein disturbing agglomeration ofthe plurality of diatom frustule portions comprises stirring.

288. The method of embodiment 286 or 287, wherein disturbingagglomeration of the plurality of diatom frustule portions comprisesshaking.

289. The method of any one of embodiments 286 to 288, wherein disturbingagglomeration of the plurality of diatom frustule portions comprisesbubbling.

290. The method of any one of embodiments 285 to 289, wherein filteringcomprises applying a sieve to the plurality of diatom frustule portions.

291. The method of embodiment 290, wherein the sieve has a mesh sizefrom about 5 microns to about 10 microns.

292. The method of embodiment 290, wherein the sieve has a mesh size ofabout 7 microns.

293. The method of any one of embodiments 267 to 292, further comprisingobtaining a washed diatom frustule portion.

294. The method of embodiment 293, wherein obtaining the washed diatomfrustule portion comprises washing the plurality of diatom frustuleportions with a cleaning solvent after removing the at least one of theorganic contaminant and the inorganic contaminant.

295. The method of embodiment 293 or 294 wherein obtaining the washeddiatom frustule portion comprises washing the diatom frustule portionhaving the at least one common characteristic with a cleaning solvent.

296. The method of embodiment 294 or 295, further comprising removingthe cleaning solvent.

297. The method of embodiment 296, wherein removing the cleaning solventcomprises sedimenting the plurality of diatom frustule portions afterremoving the at least one of the organic contaminant and the inorganiccontaminant.

298. The method of embodiment 296 or 297, wherein removing the cleaningsolvent comprises sedimenting the plurality of diatom frustule portionshaving the at least one common characteristic.

299. The method of embodiment 297 or 298, wherein sedimenting comprisescentrifuging.

300. The method of embodiment 299, wherein centrifuging comprisesapplying a centrifuge suitable for large scale processing.

301. The method of embodiment 300, wherein centrifuging comprisesapplying at least one of a disc stack centrifuge, a decanter centrifuge,and a tubular bowl centrifuge.

302. The method of any one of embodiments 295 to 301, wherein at leastone of the dispersing solvent and the cleaning solvent comprises water.

303. The method of any one of embodiments 269 to 302, wherein at leastone of dispersing the plurality of diatom frustule portions in thedispersing solvent and dispersing the plurality of diatom frustuleportions in the surfactant comprises sonicating the plurality of diatomfrustules.

304. The method of any one of embodiments 267 to 303, wherein thesurfactant comprises a cationic surfactant.

305. The method of embodiment 304, wherein the cationic surfactantcomprises at least one of a benzalkonium chloride, a cetrimoniumbromide, a lauryl methyl gluceth-10 hydroxypropyl dimonium chloride, abenzethonium chloride, a benzethonium chloride, a bronidox, admethyldioctadecylammonium chloride, and a tetramethylammoniumhydroxide.

306. The method of any one of embodiments 267 to 305, wherein thesurfactant comprises a non-ionic surfactant.

307. The method of embodiment 306, wherein the non-ionic surfactantcomprises at least one of a cetyl alcohol, a stearyl alcohol, acetostearyl alcohol, an oleyl alcohol, a polyoxyethylene glycol alkylether, an octaethylene glycol monododecyl ether, a glucoside alkylethers, a decyl glucoside, a polyoxyethylene glycol octylphenol ethers,an octylphenol ethoxylate (Triton X-100™), a nonoxynol-9, a glyceryllaurate, a polysorbate, and a poloxamer.

308. The method of any one of embodiments 267 to 307, further comprisingdispersing the plurality of diatom frustules in an additive component.

309. The method of embodiment 308, wherein dispersing the plurality ofdiatom frustules in an additive component is before dispersing theplurality of diatom frustules in the surfactant.

310. The method of embodiment 308, wherein dispersing the plurality ofdiatom frustules in an additive component is after dispersing theplurality of diatom frustules in the surfactant.

311. The method of embodiment 308, wherein dispersing the plurality ofdiatom frustules in an additive component is at least partiallysimultaneous with dispersing the plurality of diatom frustules in thesurfactant.

312. The method of any one of embodiments 308 to 311, wherein theadditive component comprises at least one of a potassium chloride, anammonium chloride, an ammonium hydroxide, and a sodium hydroxide.

313. The method of any one of embodiments 269 to 312, wherein dispersingthe plurality of diatom frustule portions in the dispersing solventcomprises obtaining a dispersion comprising about 1 weight percent toabout 5 weight percent of the plurality of diatom frustule portions.

314. The method of any one of embodiments 270 to 313, wherein removingthe organic contaminant comprises heating the plurality of diatomfrustule portions in the presence of a bleach.

315. The method of embodiment 314, wherein the bleach comprises at leastone of a hydrogen peroxide, and a nitric acid.

316. The method of embodiment 315, wherein heating comprises heating theplurality of diatom frustule portions in a solution comprising an amountof hydrogen peroxide in a range from about 10 volume percent to about 20volume percent.

317. The method of any one of embodiments 314 to 316, wherein heatingcomprises heating the plurality of diatom frustule portions for aduration of about 5 minutes to about 15 minutes.

318. The method of any one of embodiments 270 to 317, wherein removingthe organic contaminant comprises annealing the plurality of diatomfrustule portions.

319. The method of any one of embodiments 270 to 218, wherein removingthe inorganic contaminant comprises combining the plurality of diatomfrustule portions with at least one of a hydrochloric acid and asulfuric acid.

320. The method of embodiment 319, wherein combining comprises mixingthe plurality of diatom frustule portions in a solution comprising about15 volume percent to about 25 volume percent of hydrochloric acid.

321. The method of embodiment 320, wherein the mixing is for a durationof about 20 minutes to about 40 minutes.

322. A method of forming silver nanostructures on a diatom frustuleportion, the method comprising:

forming a silver seed layer on a surface of the diatom frustule portion;and forming a nanostructure on the seed layer. 323. The method ofembodiment 322, wherein the nanostructures comprises at least one of acoating, a nanowire, a nanoplate, a dense array of nanoparticles, ananobelt, and a nanodisk.

324. The method of embodiment 322 or 323, wherein the nanostructurescomprises silver.

325. The method of any one of embodiment 322 to 324, wherein forming thesilver seed layer comprises applying a cyclic heating regimen to a firstsilver contributing component and the diatom frustule portion.

326. The method of embodiment 325, wherein applying the cyclic heatingregimen comprises applying a cyclic microwave power.

327. The method of embodiment 326, wherein applying the cyclic microwavepower comprises alternating a microwave power between about 100 Watt and500 Watt.

328. The method of embodiment 327, wherein alternating comprisesalternating the microwave power every minute.

329. The method of embodiment 327 or 328, wherein alternating comprisesalternating the microwave power for a duration of about 30 minutes.

330. The method of embodiment 327 or 328, wherein alternating comprisesalternating the microwave power for a duration of about 20 minutes toabout 40 minutes.

331. The method of any one of embodiments 322 to 330, wherein formingthe silver seed layer comprises combining the diatom frustule portionwith a seed layer solution.

332. The method of embodiment 331, wherein the seed layer solutioncomprises the first silver contributing component and a seed layerreducing agent.

333. The method of embodiment 332, wherein the seed layer reducing agentis a seed layer solvent.

334. The method of embodiment 333, wherein the seed layer reducing agentand the seed layer solvent comprises a polyethylene glycol.

335. The method of embodiment 331, wherein the seed layer solutioncomprises the first silver contributing component, a seed layer reducingagent and a seed layer solvent.

336. The method of any one of embodiments 331 to 335, wherein formingthe silver seed layer further comprises mixing the diatom frustuleportion with the seed layer solution.

337. The method of embodiment 336, wherein mixing comprisesultrasonicating.

338. The method of embodiment 337, wherein the seed layer reducing agentcomprises a N,N-Dimethylformamide, the first silver contributingcomponent comprises a silver nitrate, and the seed layer solventcomprises at least one of a water and a polyvinylpyrrolidone.

339. The method of any one of embodiments 322 to 338, wherein formingthe nanostructure comprises combining the diatom frustule portion with ananostructure forming reducing agent.

340. The method of embodiment 339, wherein forming the nanostructurefurther comprises heating the diatom frustule portion after combiningthe diatom frustule portion with the nanostructure forming reducingagent.

341. The method of embodiment 340, wherein heating comprises heating toa temperature of about 120° C. to about 160° C.

342. The method of embodiment 340 or 341, wherein forming thenanostructure further comprises titrating the diatom frustule portionwith a titration solution comprising a nanostructure forming solvent anda second silver contributing component.

343. The method of embodiment 342, wherein forming the nanostructurefurther comprises mixing after titrating the diatom frustule portionwith the titration solution.

344. The method of any one of embodiments 339 to 343, wherein at leastone of the seed layer reducing agent and the nanostructure formingreducing agent comprises at least one of a hydrazine, a formaldehyde, aglucose, sodium tartrate, an oxalic acid, a formic acid, an ascorbicacid, and an ethylene glycol.

345. The method of any one of embodiments 342 to 344, wherein at leastone of the first silver contributing component and the second silvercontributing component comprises at least one of a silver salt and asilver oxide.

346. The method of embodiment 345, wherein the silver salt comprises atleast one of a silver nitrate and an ammoniacal silver nitrate, a silverchloride (AgC1), a silver cyanide (AgCN), a silver tetrafluoroborate, asilver hexafluorophosphate, and a silver ethylsulphate.

347. The method of any one of embodiments 322 to 346, wherein formingthe nanostructure is in an ambient to reduce oxide formation.

348. The method of embodiment 347, wherein the ambient comprises anargon atmosphere.

349. The method of any one of embodiments 342 to 348, wherein at leastone of the seed layer solvent and the nanostructure forming solventcomprises at least one of a propylene glycol, a water, a methanol, anethanol, a 1-propanol, a 2-propanol a 1-methoxy-2-propanol, a 1-butanol,a 2-butanol a 1-pentanol, a 2-pentanol, a 3-pentanol, a 1-hexanol, a2-hexanol, a 3-hexanol, an octanol, a 1-octanol, a 2-octanol, a3-octanol, a tetrahydrofurfuryl alcohol (THFA), a cyclohexanol, acyclopentanol, a terpineol, a butyl lactone; a methyl ethyl ether, adiethyl ether, an ethyl propyl ether, a polyethers, a diketones, acyclohexanone, a cyclopentanone, a cycloheptanone, a cyclooctanone, anacetone, a benzophenone, an acetylacetone, an acetophenone, acyclopropanone, an isophorone, a methyl ethyl ketone, an ethyl acetate,a dimethyl adipate, a propylene glycol monomethyl ether acetate, adimethyl glutarate, a dimethyl succinate, a glycerin acetate, acarboxylates, a propylene carbonate, a glycerin, a diol, a triol, atetraol, a pentanol, an ethylene glycol, a diethylene glycol, apolyethylene glycol, a propylene glycol, a dipropylene glycol, a glycolether, a glycol ether acetate, a 1,4-butanediol, a 1,2-butanediol, a2,3-butanediol, a 1,3-propanediol, a 1,4-butanediol, a 1,5-pentanediol,a 1,8-octanediol, a 1,2-propanediol, a 1,3-butanediol, a1,2-pentanediol, an etohexadiol, a p-menthane-3,8-diol, a2-methyl-2,4-pentanediol, a tetramethyl urea, a n-methylpyrrolidone, anacetonitrile, a tetrahydrofuran (THF), a dimethyl formamide (DMF), aN-methyl formamide (NMF), a dimethyl sulfoxide (DMSO), a thionylchloride and a sulfuryl chloride.

350. The method of any one of embodiments 322 to 349, wherein the diatomfrustule portion comprises a broken diatom frustule portion.

351. The method of any one of embodiments 322 to 349, wherein the diatomfrustule portion comprises an unbroken diatom frustule portion.

352. The method of any one of embodiments 322 to 351, wherein the diatomfrustule portion is obtained through a diatom frustule portionseparation process.

353. The method of embodiment 352, wherein the process comprises atleast one of using a surfactant to reduce an agglomeration of aplurality of diatom frustule portions and using a disc stack centrifuge.

354. A method of forming zinc-oxide nanostructures on a diatom frustuleportion, the method comprising:

-   -   forming a zinc-oxide seed layer on a surface of the diatom        frustule portion; and    -   forming a nanostructure on the zinc-oxide seed layer.

355. The method of embodiment 354, wherein the nanostructure comprisesat least one of a nanowire, a nanoplate, a dense array of nanoparticles,a nanobelt, and a nanodisk.

356. The method of embodiment 354 or 355, wherein the nanostructurescomprises zinc-oxide.

357. The method of any one of embodiments 354 to 356, wherein formingthe zinc-oxide seed layer comprises heating a first zinc contributingcomponent and the diatom frustule portion.

358. The method of embodiment 357, wherein heating the first zinccontributing component and the diatom frustule portion comprises heatingto a temperature in a range from about 175° C. to about 225° C.

359. The method of any one of embodiments 354 to 358, wherein formingthe nanostructure comprises applying a heating regimen to the diatomfrustule portion having the zinc-oxide seed layer in the presence of ananostructure forming solution comprising a second zinc contributingcomponent.

360. The method of embodiment 359, wherein the heating regimen comprisesheating to a nanostructure forming temperature.

361. The method of embodiment 360, wherein the nanostructure formingtemperature is from about 80° C. to about 100° C.

362. The method of embodiment 360 or 361, wherein the heating is for aduration of about one to about three hours.

363. The method of any one of embodiments 359 to 362, wherein theheating regimen comprises applying a cyclic heating routine.

364. The method of embodiment 363, wherein the cyclic heating routinecomprises applying a microwave heating to the diatom frustule portionhaving the zinc-oxide seed layer for a heating duration and then turningthe microwaving heating off for a cooling duration, for a total cyclicheating duration.

365. The method of embodiment 364, wherein the heating duration is about1 minute to about 5 minutes.

366. The method of embodiment 364 or 365, wherein the cooling durationis about 30 seconds to about 5 minutes.

367. The method of any one of embodiments 364 to 366, wherein the totalcyclic heating duration is about 5 minutes to about 20 minutes.

368. The method of any one of embodiments 364 to 367, wherein applyingthe microwave heating comprises applying about 480 Watt to about 520Watt of microwave power.

369. The method of any one of embodiments 364 to 367, wherein applyingthe microwave heating comprises applying about 80 Watt to about 120 Wattof microwave power.

370. The method of any one of embodiments 359 to 369, wherein at leastone of the first zinc contributing component and the second zinccontributing component comprise at least one of a zinc acetate, a zincacetate hydrate, a zinc nitrate, a zinc nitrate hexahydrate, a zincchloride, a zinc sulfate, and a sodium zincate.

371. The method of any one of embodiments 359 to 370, wherein thenanostructure forming solution comprises a base.

372. The method of embodiment 371, wherein the base comprises at leastone of a sodium hydroxide, an ammonium hydroxide, potassium hydroxide, ateramethylammonium hydroxide, a lithium hydroxide, ahexamethylenetetramine, an ammonia solution, a sodium carbonate, and aethylenediamine.

373. The method of any one of embodiments 354 to 372, wherein formingthe nanostructure further comprises adding an additive component.

374. The method of embodiment 373, wherein the additive componentcomprises at least one of a tributylamine, a triethylamine, atriethanolamine, a diisopropylamine, an ammonium phosphate, a1,6-hexadianol, a triethyldiethylnol, an isopropylamine, acyclohexylamine, a n-butylamine, an ammonium chloride, ahexamethylenetetramine, an ethylene glycol, an ethanoamine, apolyvinylalcohol, a polyethylene glycol, a sodium dodecyl sulphate, acetyltrimethyl ammonium bromide, and a carbamide.

375. The method of any one of embodiments 359 to 374, wherein at leastone of the nanostructure forming solution and a zinc-oxide seed layerforming solution comprises a solvent, the solvent comprising at leastone of a propylene glycol, a water, a methanol, an ethanol, a1-propanol, a 2-propanol a 1-methoxy-2-propanol, a 1-butanol, a2-butanol a 1-pentanol, a 2-pentanol, a 3-pentanol, a 1-hexanol, a2-hexanol, a 3-hexanol, an octanol, a 1-octanol, a 2-octanol, a3-octanol, a tetrahydrofurfuryl alcohol (THFA), a cyclohexanol, acyclopentanol, a terpineol, a butyl lactone; a methyl ethyl ether, adiethyl ether, an ethyl propyl ether, a polyethers, a diketones, acyclohexanone, a cyclopentanone, a cycloheptanone, a cyclooctanone, anacetone, a benzophenone, an acetylacetone, an acetophenone, acyclopropanone, an isophorone, a methyl ethyl ketone, an ethyl acetate,a dimethyl adipate, a propylene glycol monomethyl ether acetate, adimethyl glutarate, a dimethyl succinate, a glycerin acetate, acarboxylates, a propylene carbonate, a glycerin, a diol, a triol, atetraol, a pentanol, an ethylene glycol, a diethylene glycol, apolyethylene glycol, a propylene glycol, a dipropylene glycol, a glycolether, a glycol ether acetate, a 1,4-butanediol, a 1,2-butanediol, a2,3-butanediol, a 1,3-propanediol, a 1,4-butanediol, a 1,5-pentanediol,a 1,8-octanediol, a 1,2-propanediol, a 1,3-butanediol, a1,2-pentanediol, an etohexadiol, a p-menthane-3,8-diol, a2-methyl-2,4-pentanediol, a tetramethyl urea, a n-methylpyrrolidone, anacetonitrile, a tetrahydrofuran (THF), a dimethyl formamide (DMF), aN-methyl formamide (NMF), a dimethyl sulfoxide (DMSO), a thionylchloride and a sulfuryl chloride.

376. The method of any one of embodiments 354 to 375, wherein the diatomfrustule portion comprises a broken diatom frustule portion.

377. The method of any one of embodiments 354 to 375, wherein the diatomfrustule portion comprises an unbroken diatom frustule portion.

378. The method of any one of embodiments 354 to 375, wherein the diatomfrustule portion is obtained through a diatom frustule portionseparation process.

379. The method of embodiment 378, wherein the process comprises atleast one of using a surfactant to reduce an agglomeration of aplurality of diatom frustule portions and using a disc stack centrifuge.

380. A method of forming carbon nanostructures on a diatom frustuleportion, the method comprising:

-   -   forming a metal seed layer on a surface of the diatom frustule        portion; and    -   forming a carbon nanostructure on the seed layer. 381. The        method of embodiment 380, wherein the carbon nanostructure        comprises a carbon nanotube.

382. The method of embodiment 381, wherein the carbon nanotube compriseat least one of a single-walled carbon nanotube and a multi-walledcarbon nanotube.

383. The method of any one of embodiments 380 to 382, wherein formingthe metal seed layer comprises spray coating the surface of the diatomfrustule portion.

384. The method of any one of embodiments 380 to 383, wherein formingthe metal seed layer comprises introducing the surface of the diatomfrustule portion to at least one of a liquid comprising the metal, a gascomprising the metal and the solid comprising a metal.

385. The method of any one of embodiments 380 to 384, wherein formingthe carbon nanostructure comprises using chemical vapor deposition(CVD).

386. The method of any one of embodiments 380 to 385, wherein formingthe carbon nanostructure comprises exposing the diatom frustule portionto a nanostructure forming reducing gas after exposing the diatomfrustule portion to a nanostructure forming carbon gas.

387. The method of any one of embodiments 380 to 385, wherein formingthe carbon nanostructure comprises exposing the diatom frustule portionto a nanostructure forming reducing gas before exposing the diatomfrustule portion to a nanostructure forming carbon gas.

388. The method of any one of embodiments 380 to 385, wherein formingthe carbon nanostructure comprises exposing the diatom frustule portionto a nanostructure forming gas mixture comprising a nanostructureforming reducing gas and a nanostructure forming carbon gas.

389. The method of embodiment 388, wherein the nanostructure forming gasmixture further comprises a neutral gas.

390. The method of embodiment 389, wherein the neutral gas comprisesargon.

391. The method of any one of embodiments 380 to 390, wherein the metalcomprises at least one of a nickel, an iron, a cobalt, acobalt-molibdenium bimetallic, a copper, a gold, a silver, a platinum, apalladium, a manganese, an aluminum, a magnesium, a chromium, anantimony, an aluminum-iron-molybdenum (Al/Fe/Mo), an iron pentacarbonyl(Fe(CO)₅)), an iron (III) nitrate hexahydrate ((Fe(NO₃)₃·6H₂O), acolbalt (II) chloride hexahydrate (CoCl₂·6H₂O), an ammonium molybdatetetrahydrate ((NH₄)₆Mo₇O₂₄·4H₂O), a molybdenum (VI) dichloride dioxideMoO₂Cl₂, and an alumina nanopowder.

392. The method of any one of embodiments 286 to 391, wherein thenanostructure forming reducing gas comprises at least one of an ammonia,a nitrogen, and a hydrogen.

393. The method of any one of embodiments 286 to 392, wherein thenanostructure forming carbon gas comprises at least one of an acetylene,an ethylene, an ethanol, a methane, a carbon oxide, and a benzene.

394. The method of any one of embodiments 380 to 393, wherein formingthe metal seed layer comprises forming a silver seed layer.

395. The method of embodiment 394, wherein forming the silver seed layercomprises forming a silver nanostructure on the surface of the diatomfrustule portion.

396. The method of any one of embodiments 380 to 395, wherein the diatomfrustule portion comprises a broken diatom frustule portion.

397. The method of any one of embodiments 380 to 395, wherein the diatomfrustule portion comprises an unbroken diatom frustule portion.

398. The method of any one of embodiments 380 to 397, wherein the diatomfrustule portion is obtained through a diatom frustule portionseparation process.

399. The method of embodiment 398, wherein the process comprises atleast one of using a surfactant to reduce an agglomeration of aplurality of diatom frustule portions and using a disc stack centrifuge.

400. A method of fabricating a silver ink, the method comprising:

-   -   combining an ultraviolet light sensitive component and a        plurality of diatom frustule portions having a silver        nanostructure on a surface of the plurality of diatom frustule        portions, the surface comprising a plurality of perforations.

401. The method of embodiment 400, further comprising forming a silverseed layer on the surface of the plurality of diatom frustule portions.

402. The method of embodiment 400 or 401, further comprising forming thesilver nanostructure on the seed layer.

403. The method of any one of embodiments 400 to 402, wherein theplurality of diatom frustule portions comprises a plurality of brokendiatom frustule portions.

404. The method of any one of embodiments 400 to 403, wherein theplurality of diatom frustule portions comprises a plurality of diatomfrustule flakes.

405. The method of any one of embodiments 400 to 404, wherein the silverink is depositable in a layer having a thickness of about 5 microns toabout 15 microns after curing.

406. The method of any one of embodiments 400 to 405, wherein at leastone of the plurality of perforations comprises a diameter of about 250nanometers to about 350 nanometers.

407. The method of any one of embodiments 400 to 406, wherein the silvernanostructure comprises a thickness of about 10 nanometers to about 500nanometers.

408. The method of any one of embodiments 400 to 407, wherein the silverink comprises an amount of diatom frustules within a range of about 50weight percent to about 80 weight percent.

409. The method of any one of embodiments 401 to 408, wherein formingthe silver seed layer comprises forming the silver seed layer on asurface within the plurality of perforations to form a plurality ofsilver seed plated perforations.

410. The method of any one of embodiments 401 to 409, wherein formingthe silver seed layer comprises forming the silver seed layer onsubstantially all surfaces of the plurality of diatom frustule portions.

411. The method of any one of embodiments 402 to 410, wherein formingthe silver nanostructure comprises forming the silver nanostructure on asurface within the plurality of perforations to form a plurality ofsilver nanostructure plated perforations.

412. The method of any one of embodiments 402 to 411, wherein formingthe silver nanostructure comprises forming the silver nanostructure onsubstantially all surfaces of the plurality of diatom frustule portions.

413. The method of any one of embodiments 400 to 412, wherein theultraviolet light sensitive component is sensitive to an opticalradiation having a wavelength shorter than a dimension of the pluralityof perforations.

414. The method of any one of embodiments 411 to 413, wherein theultraviolet light sensitive component is sensitive to an opticalradiation having a wavelength shorter than a dimension of at least oneof the plurality of silver seed plated perforations and the plurality ofsilver nanostructure plated perforations.

415. The method of any one of embodiments 400 to 414, wherein combiningthe plurality of diatom frustule portions with the ultraviolet lightsensitive component comprises combining the plurality of diatom frustuleportions with a photoinitiation synergist agent.

416. The method of embodiment 415, wherein the photoinitiation synergistagent comprises at least one of an ethoxylated hexanediol acrylate, apropoxylated hexanediol acrylate, an ethoxylated trimethylpropanetriacrylate, a triallyl cyanurate and an acrylated amine.

417. The method of any one of embodiments 400 to 416, wherein combiningthe plurality of diatom frustule portions with the ultraviolet lightsensitive component comprises combining the plurality of diatom frustuleportions with a photoinitiator agent.

418. The method of embodiment 417, wherein the photoinitiator agentcomprises at least one of a2-methyl-1-(4-methylthio)phenyl-2-morpholinyl-1-propanon and anisopropyl thioxothanone.

419. The method of any one of embodiments 400 to 418, wherein combiningthe plurality of diatom frustule portions with the ultraviolet lightsensitive component comprises combining the plurality of diatom frustuleportions with a polar vinyl monomer.

420. The method of embodiment 419, wherein the polar vinyl monomercomprises at least one of a n-vinyl-pyrrolidone and an-vinylcaprolactam.

421. The method of any one of embodiments 400 to 420, further comprisingcombining the plurality of diatom frustule portions with a rheologymodifying agent.

422. The method of any one of embodiments 400 to 421, further comprisingcombining the plurality of diatom frustule portions with a cros slinkingagent.

423. The method of any one of embodiments 400 to 422, further comprisingcombining the plurality of diatom frustule portions with a flow andlevel agent.

424. The method of any one of embodiments 400 to 423, further comprisingcombining the plurality of diatom frustule portions with at least one ofan adhesion promoting agent, a wetting agent, and a viscosity reducingagent.

425. The method of any one of embodiments 400 to 424, wherein the silvernanostructure comprises at least one of a coating, a nanowire, ananoplate, a dense array of nanoparticles, a nanobelt, and a nanodisk.

426. The method of any one of embodiment 401 to 425, wherein forming thesilver seed layer comprises applying a cyclic heating regimen to a firstsilver contributing component and the plurality of diatom frustuleportions.

427. The method of any one of embodiments 401 to 426, wherein formingthe silver seed layer comprises combining the diatom frustule portionwith a seed layer solution.

428. The method of embodiment 427, wherein the seed layer solutioncomprises the first silver contributing component and a seed layerreducing agent.

429. The method of any one of embodiments 402 to 428, wherein formingthe silver nanostructure comprises combining the diatom frustule portionwith a nanostructure forming reducing agent.

430. The method of embodiment 429, wherein forming the silvernanostructure further comprises heating the diatom frustule portionafter combining the diatom frustule portion with the nanostructureforming reducing agent.

431. The method of any one of embodiments 402 to 430, wherein formingthe silver nanostructure further comprises titrating the diatom frustuleportion with a titration solution comprising a nanostructure formingsolvent and a second silver contributing component.

432. The method of any one of embodiments 400 to 431, wherein theplurality of diatom frustule portions are obtained through a diatomfrustule portion separation process.

433. The method of embodiment 432, wherein the process comprises atleast one of using a surfactant to reduce an agglomeration of aplurality of diatom frustule portions and using a disc stack centrifuge.

434. A conductive silver ink comprising:

-   -   an ultraviolet light sensitive component; and    -   a plurality of diatom frustule portions having a silver        nanostructure on a surface of the plurality of diatom frustule        portions, the surface comprising a plurality of perforations.

435. The conductive silver ink of embodiment 434, wherein the pluralityof diatom frustule portions comprises a plurality of broken diatomfrustule portion.

436. The conductive silver ink of embodiment 434 or 435, wherein theplurality of diatom frustule portions comprises a plurality of diatomfrustule flakes.

437. The conductive silver ink of any one of embodiments 434 to 436,wherein the silver ink is depositable in a layer having a thickness ofabout 5 microns to about 15 microns after curing.

438. The conductive silver ink of any one of embodiments 434 to 437,wherein at least one of the plurality of perforations comprises adiameter of about 250 nanometers to about 350 nanometers.

439. The conductive silver ink of any one of embodiments 434 to 438,wherein the silver nanostructure comprises a thickness of about 10nanometers to about 500 nanometers.

440. The conductive silver ink of any one of embodiments 434 to 439,wherein the silver ink comprises an amount of diatom frustules within arange of about 50 weight percent to about 80 weight percent.

441. The conductive silver ink of any one of embodiments 434 to 440,wherein at least one of the plurality of perforations comprises asurface having a silver nanostructure.

442. The conductive silver ink of any one of embodiments 434 to 441,wherein at least one of the plurality of perforations comprises asurface having a silver seed layer.

443. The conductive silver ink of any one of embodiments 434 to 442,wherein substantially all surfaces of the plurality of diatom frustuleportions comprises a silver nanostructure.

444. The conductive silver ink of any one of embodiments 434 to 443,wherein the ultraviolet light sensitive component is sensitive to anoptical radiation having a wavelength shorter than a dimension of theplurality of perforations.

445. The conductive silver ink of any one of embodiments 434 to 444,wherein the conductive silver ink is curable by an ultravioletradiation.

446. The conductive silver ink of embodiment 445, wherein the conductivesilver ink is curable when deposited in a layer having a thickness ofabout 5 microns to about 15 microns after curing.

447. The conductive silver ink of embodiment 445 or 446, wherein theplurality of perforations has a dimension configured to allow theultraviolet radiation to pass through the plurality of diatom frustuleportions.

448. The conductive silver ink of any one of embodiments 434 to 447,wherein the conductive silver ink is thermally curable.

449. The conductive silver ink of any one of embodiments 434 to 448,wherein the ultraviolet light sensitive component comprises aphotoinitiation synergist agent.

450. The conductive silver ink of embodiment 449, wherein thephotoinitiation synergist agent comprises at least one of an ethoxylatedhexanediol acrylate, a propoxylated hexanediol acrylate, an ethoxylatedtrimethylpropane triacrylate, a triallyl cyanurate and an acrylatedamine.

451. The conductive silver ink of any one of embodiments 434 to 450,wherein the ultraviolet light sensitive component comprises aphotoinitiator agent.

452. The conductive silver ink of embodiment 451, wherein thephotoinitiator agent comprises at least one of a2-methyl-1-(4-methylthio)phenyl-2-morpholinyl-1-propanon and anisopropyl thioxothanone.

453. The conductive silver ink of any one of embodiments 434 to 452,wherein the ultraviolet light sensitive component comprises a polarvinyl monomer.

454. The conductive silver ink of embodiment 453, wherein the polarvinyl monomer comprises at least one of a n-vinyl-pyrrolidone and an-vinylcaprolactam.

455. The conductive silver ink of any one of embodiments 434 to 454,further comprising at least one of a rheology modifying agent, acrosslinking agent, a flow and level agent, an adhesion promoting agent,a wetting agent, and a viscosity reducing agent.

456. The conductive silver ink of any one of embodiments 434 to 455,wherein the silver nanostructure comprises at least one of a coating, ananowire, a nanoplate, a dense array of nanoparticles, a nanobelt, and ananodisk.

457. A method of fabricating a silver film, the method comprising:

-   -   curing a mixture comprising an ultraviolet light sensitive        component and a plurality of diatom frustule portions having a        silver nanostructure on a surface of the plurality of diatom        frustule portions, the surface comprising a plurality of        perforations.

458. The method of embodiment 457, further comprising forming a silverseed layer on the surface of the plurality of diatom frustule portions.

459. The method of embodiment 457 or 458, further comprising forming thesilver nanostructure on the seed layer.

460. The method of any one of embodiments 457 to 459, further comprisingcombining the plurality of diatom frustule portions with the ultravioletlight sensitive component to form a silver ink.

461. The method of any one of embodiments 457 to 460, wherein theplurality of diatom frustule portions comprises a plurality of brokendiatom frustule portions.

462. The method of any one of embodiments 457 to 461, wherein theplurality of diatom frustule portions comprises a plurality of diatomfrustule flakes.

463. The method of any one of embodiments 460 to 462, wherein the silverink is depositable in a layer having a thickness of about 5 microns toabout 15 microns after curing.

464. The method of any one of embodiments 457 to 463, wherein at leastone of the plurality of perforations comprises a diameter of about 250nanometers to about 350 nanometers.

465. The method of any one of embodiments 457 to 464, wherein the silvernanostructure comprises a thickness of about 10 nanometers to about 500nanometers.

466. The method of any one of embodiments 460 to 465, wherein the silverink comprises an amount of diatom frustules within a range of about 50weight percent to about 80 weight percent.

467. The method of any one of embodiments 458 to 466, wherein formingthe silver seed layer comprises forming the silver seed layer on asurface within the plurality of perforations to form a plurality ofsilver seed plated perforations.

468. The method of any one of embodiments 458 to 467, wherein formingthe silver seed layer comprises forming the silver seed layer onsubstantially all surfaces of the plurality of diatom frustule portions.

469. The method of any one of embodiments 459 to 468, wherein formingthe silver nanostructure comprises forming the silver nanostructure on asurface within the plurality of perforations to form a plurality ofsilver nanostructure plated perforations.

470. The method of any one of embodiments 459 to 469, wherein formingthe silver nanostructure comprises forming the silver nanostructure onsubstantially all surfaces of the plurality of diatom frustule portions.

471. The method of any one of embodiments 457 to 470, wherein curing themixture comprises exposing the mixture to an ultraviolet light having awavelength shorter than a dimension of the plurality of perforations.

472. The method of any one of embodiments 469 to 471, wherein curing themixture comprises exposing the mixture to an ultraviolet light having awavelength shorter than a dimension of at least one of the plurality ofsilver seed plated perforations and the plurality of silvernanostructure plated perforations.

473. The method of any one of embodiments 457 to 472, wherein curing themixture comprises thermally curing the mixture.

474. The method of any one of embodiments 457 to 473, wherein theultraviolet light sensitive component is sensitive to an opticalradiation having a wavelength shorter than a dimension of the pluralityof perforations.

475. The method of any one of embodiments 469 to 474, wherein theultraviolet light sensitive component is sensitive to an opticalradiation having a wavelength shorter than a dimension of at least oneof the plurality of silver seed plated perforations and the plurality ofsilver nanostructure plated perforations.

476. The method of any one of embodiments 460 to 475, wherein combiningthe plurality of diatom frustule portions with the ultraviolet lightsensitive component comprises combining the plurality of diatom frustuleportions with a photoinitiation synergist agent.

477. The method of embodiment 476, wherein the photoinitiation synergistagent comprises at least one of an ethoxylated hexanediol acrylate, apropoxylated hexanediol acrylate, an ethoxylated trimethylpropanetriacrylate, a triallyl cyanurate and an acrylated amine.

478. The method of any one of embodiments 460 to 477, wherein combiningthe plurality of diatom frustule portions with the ultraviolet lightsensitive component comprises combining the plurality of diatom frustuleportions with a photoinitiator agent.

479. The method of embodiment 478, wherein the photoinitiator agentcomprises at least one of a2-methyl-1-(4-methylthio)phenyl-2-morpholinyl-1-propanon and anisopropyl thioxothanone.

480. The method of any one of embodiments 460 to 479, wherein combiningthe plurality of diatom frustule portions with the ultraviolet lightsensitive component comprises combining the plurality of diatom frustuleportions with a polar vinyl monomer.

481. The method of embodiment 480, wherein the polar vinyl monomercomprises at least one of a n-vinyl-pyrrolidone and an-vinylcaprolactam.

482. The method of any one of embodiments 457 to 481, further comprisingcombining the plurality of diatom frustule portions with a rheologymodifying agent.

483. The method of any one of embodiments 457 to 482, further comprisingcombining the plurality of diatom frustule portions with a cros slinkingagent.

484. The method of any one of embodiments 457 to 483, further comprisingcombining the plurality of diatom frustule portions with a flow andlevel agent.

485. The method of any one of embodiments 457 to 484, further comprisingcombining the plurality of diatom frustule portions with at least one ofan adhesion promoting agent, a wetting agent, and a viscosity reducingagent.

486. The method of any one of embodiments 457 to 485, wherein the silvernanostructure comprises at least one of a coating, a nanowire, ananoplate, a dense array of nanoparticles, a nanobelt, and a nanodisk.

487. The method of any one of embodiment 458 to 486, wherein forming thesilver seed layer comprises applying a cyclic heating regimen to a firstsilver contributing component and the plurality of diatom frustuleportions.

488. The method of any one of embodiments 458 to 487, wherein formingthe silver seed layer comprises combining the diatom frustule portionwith a seed layer solution.

489. The method of embodiment 488, wherein the seed layer solutioncomprises the first silver contributing component and a seed layerreducing agent.

490. The method of any one of embodiments 459 to 489, wherein formingthe silver nanostructure comprises combining the diatom frustule portionwith a nanostructure forming reducing agent.

491. The method of embodiment 490, wherein forming the silvernanostructure further comprises heating the diatom frustule portionafter combining the diatom frustule portion with the nanostructureforming reducing agent.

492. The method of any one of embodiments 459 to 491, wherein formingthe silver nanostructure further comprises titrating the diatom frustuleportion with a titration solution comprising a nanostructure formingsolvent and a second silver contributing component.

493. The method of any one of embodiments 457 to 492, wherein theplurality of diatom frustule portions are obtained through a diatomfrustule portion separation process.

494. The method of embodiment 493, wherein the process comprises atleast one of using a surfactant to reduce an agglomeration of aplurality of diatom frustule portions and using a disc stack centrifuge.

495. A conductive silver film comprising:

-   -   a plurality of diatom frustule portions having a silver        nanostructure on a surface of each of the plurality of diatom        frustule portions, the surface comprising a plurality of        perforations.

496. The conductive silver film of embodiment 495, wherein the pluralityof diatom frustule portions comprises a plurality of broken diatomfrustule portion.

497. The conductive silver film of embodiment 495 or 496, wherein theplurality of diatom frustule portions comprises a plurality of diatomfrustule flakes.

498. The conductive silver film of any one of embodiments 495 to 497,wherein at least one of the plurality of perforations comprises adiameter of about 250 nanometers to about 350 nanometers.

499. The conductive silver film of any one of embodiments 495 to 498,wherein the silver nanostructure comprises a thickness of about 10nanometers to about 500 nanometers.

500. The conductive silver film of any one of embodiments 495 to 499,wherein at least one of the plurality of perforations comprises asurface having a silver nanostructure.

501. The conductive silver film of any one of embodiments 495 to 500,wherein at least one of the plurality of perforations comprises asurface having a silver seed layer.

502. The conductive silver film of any one of embodiments 495 to 501,wherein substantially all surfaces of the plurality of diatom frustuleportions comprises a silver nanostructure.

503. The conductive silver film of any one of embodiments 495 to 502,wherein the silver nanostructure comprises at least one of a coating, ananowire, a nanoplate, a dense array of nanoparticles, a nanobelt, and ananodisk.

504. The conductive silver film of any one of embodiments 495 to 503,further comprising a binder resin.

505. A printed energy storage device comprising:

-   -   a first electrode;    -   a second electrode; and    -   a separator between the first electrode and the second        electrode, at least one of the first electrode and the second        electrode including a plurality of frustules comprising        manganese-containing nanostructures.

506. The device of embodiment 505, wherein the frustules have asubstantially uniform property, the substantially uniform propertyincluding at least one of a frustule shape, a frustule dimension, afrustule porosity, a frustule mechanical strength, a frustule material,and a degree of brokenness of a frustule.

507. The device of embodiment 505 or 506, wherein themanganese-containing nanostructures comprise an oxide of manganese.

508. The device of embodiment 507, wherein the oxide of manganesecomprises manganese(II,III) oxide.

509. The device of embodiment 507 or 508, wherein the oxide of manganesecomprises manganese oxyhydroxide.

510. The device of any one of embodiments 505-509, wherein at least oneof the first electrode and the second electrode comprises frustulescomprising zinc-oxide nano structures.

511. The device of embodiment 510, wherein the zinc-oxide nanostructurescomprise at least one of a nano-wire and a nano-plate.

512. The device of any one of embodiments 505-511, wherein themanganese-containing nanostructures cover substantially all surfaces ofthe frustules.

513. A membrane of an energy storage device, the membrane comprisingfrustules comprising manganese-containing nanostructures.

514. The membrane of embodiment 513, wherein the manganese-containingnanostructures comprise an oxide of manganese.

515. The membrane of embodiment 514, wherein the oxide of manganesecomprises manganese(II,III) oxide.

516. The membrane of embodiment 514 or 515, wherein the oxide ofmanganese comprises manganese oxyhydroxide.

517. The membrane of any one of embodiments 513-516, wherein at leastsome of the manganese-containing nanostructures comprise a nano-fiber.

518. The membrane of any one of embodiments 513-517, wherein at leastsome of the manganese-containing nanostructures have a tetrahedralshape.

519. The membrane of any one of embodiments 513-518, wherein the energystorage device comprises a zinc-manganese battery.

520. An ink for a printed film, the ink comprising:

-   -   a solution; and    -   frustules comprising manganese-containing nanostructures        dispersed in the solution.

521. The ink of embodiment 520, wherein the manganese-containingnanostructures comprise an oxide of manganese.

522. The ink of embodiment 520 or 521, wherein the manganese-containingnanostructures comprises at least one of MnO_(2,) MnO, Mn₂O₃, MnOOH, andMn₃O_(4.)

523. The ink of any one of embodiments 520-522, wherein at least some ofthe manganese-containing nanostructures comprise a nano-fiber.

524. The ink of any one of embodiments 520-523, wherein at least some ofthe manganese-containing nanostructures have a tetrahedral shape.

525. A method of forming manganese-containing nanostructures on a diatomfrustule portion, the method comprising:

-   -   adding the frustules to an oxygenated manganese acetate        solution; and    -   heating the frustules and the oxygenated manganese acetate        solution.

526. The method of embodiment 525, further comprising forming theoxygenated manganese acetate solution, wherein forming oxygenatedmanganese acetate solution comprises dissolving manganese(II) acetate inoxygenated water.

527. The method of embodiment 526, wherein concentration of themanganese(II) acetate in the oxygenated manganese acetate solution isbetween about 0.05 M and about 1.2 M.

528. The method of any one of embodiments 525-527, further comprisingforming the oxygenated manganese acetate solution, wherein formingoxygenated manganese acetate solution comprises dissolving a manganesesalt in oxygenated water.

529. The method of embodiment 528, further comprising adding anoxidizing agent to the oxygenated manganese acetate solution.

530. The method of embodiment 529, wherein the oxidizing agent comprisesperoxide.

531. The method of any one of embodiments 526-530, further comprisingforming the oxygenated water, wherein forming oxygenated water comprisesbubbling oxygen gas into water.

532. The method of embodiment 531, wherein bubbling the oxygen gas intothe water so for a duration of about 10 minutes to about 60 minutes.

533. The method of any one of embodiments 525-532, wherein a weightpercentage of the frustules in the oxygenated manganese acetate solutionis between about 0.01 wt % and about 1 wt %.

534. The method of any one of embodiments 525-533, further comprisingthermally treating the frustules and the oxygenated manganese acetatesolution.

535. The method of embodiment 534, wherein thermally treating thefrustules and the oxygenated manganese acetate solution comprises usinga thermal technique.

536. The method of embodiment 535, wherein using the thermal techniquecomprises maintaining the frustules and the oxygenated manganese acetatesolution at a temperature for between about 15 hours and about 40 hours.

537. The method of embodiment 536, wherein the temperature is betweenabout 50° C. and about 90° C.

538. The method of embodiment 535, wherein using the thermal techniquecomprises maintaining the frustules and the oxygenated manganese acetatesolution at a temperature between about 50° C. and about 90° C.

539. The method of any one of embodiments 534-538, wherein thermallytreating the frustules and the oxygenated manganese acetate solutioncomprises using a microwave technique.

540. The method of embodiment 539, wherein using the thermal techniquecomprises maintaining the frustules and the oxygenated manganese acetatesolution at a temperature for between about 10 minutes and about 120minutes.

541. The method of embodiment 540, wherein the temperature is betweenabout 50° C. and about 150° C.

542. The method of embodiment 539, wherein using the thermal techniquecomprises maintaining the frustules and the oxygenated manganese acetatesolution at a temperature between about 50° C. and about 150° C.

543. The method of any one of embodiments 525-542, whereincarbon-containing nanostructures cover some surfaces of the frustules.

544. The method of embodiment 543, wherein the carbon-containingnanostructures comprise carbon nanotubes.

545. The method of embodiment 543 or 544, wherein the carbon-containingnanostructures comprise carbon nano-onions.

546. The method of any one of embodiments 543-545, wherein thecarbon-containing nanostructures comprise reduced graphene oxide.

547. The device of any one of embodiments 505-512, wherein themanganese-containing nanostructures cover some surfaces of the frustulesand carbon-containing nanostructures cover other surfaces of thefrustules, the manganese-containing nanostructures interspersed with thecarbon-containing nanostructures.

548. The device of embodiment 547, wherein the carbon-containingnanostructures comprise carbon nanotubes.

549. The device of embodiment 547 or 548, wherein the carbon-containingnanostructures comprise carbon nano-onions.

550. The device of any one of embodiments 547-549, wherein thecarbon-containing nanostructures comprise reduced graphene oxide.

551. The membrane of any one of embodiments 513-519, wherein themanganese-containing nanostructures cover some surfaces of the frustulesand carbon-containing nanostructures cover other surfaces of thefrustules, the manganese-containing nanostructures interspersed with thecarbon-containing nanostructures.

552. The membrane of embodiment 551, wherein the carbon-containingnanostructures comprise carbon nanotubes.

553. The membrane of embodiment 551 or 552, wherein thecarbon-containing nanostructures comprise carbon nano-onions.

554. The membrane of any one of embodiments 551-554, wherein thecarbon-containing nanostructures comprise reduced graphene oxide.

555. The ink of any one of embodiments 520-524, wherein themanganese-containing nanostructures cover some surfaces of the frustulesand carbon-containing nanostructures cover other surfaces of thefrustules, the manganese-containing nanostructures interspersed with thecarbon-containing nanostructures

556. The ink of embodiment 555, wherein the carbon-containingnanostructures comprise carbon nanotubes.

557. The ink of embodiment 555 or 556, wherein the carbon-containingnanostructures comprise carbon nano-onions.

558. The ink of any one of embodiments 555-557, wherein thecarbon-containing nanostructures comprise reduced graphene oxide.

559. An energy storage device, comprising:

-   -   a cathode comprising a first plurality of frustules, wherein the        first plurality of frustules comprises nano structures        comprising an oxide of manganese; and    -   an anode comprising a second plurality of frustules, wherein the        second plurality of frustules comprises nanostructures        comprising zinc oxide.

560. The energy storage device of embodiment 559, wherein the oxide ofmanganese comprises MnO.

561. The energy storage device of embodiment 559 or 560, wherein theoxide of manganese comprises Mn₃O_(4.)

562. The energy storage device of any one of embodiments 559 to 561,wherein the oxide of manganese comprises at least one of Mn₂O₃, andMnOOH.

563. The energy storage device of any one of embodiments 559 to 562,wherein at least one of the first plurality of frustules comprises about5 weight % to about 95 weight % of the oxide of manganese.

564. The energy storage device of embodiment 563, wherein the at leastone of the first plurality of frustules comprises about 75 weight % toabout 95 weight % of the oxide of manganese.

565. The energy storage device of any one of embodiments 559 to 564,wherein at least one of the second plurality of frustules comprisesabout 5 weight % to about 95 weight % of the zinc oxide.

566. The energy storage device of embodiment 565, wherein the at leastone of the second plurality of frustules comprises about 50 weight % toabout 60 weight % of the zinc oxide.

567. The energy storage device of any one of embodiments 559 to 566,wherein the anode further comprises an electrolyte salt.

568. The energy storage device of embodiment 567, wherein theelectrolyte salt comprises a zinc salt.

569. The energy storage device of any one of embodiments 559 to 568,wherein at least one of the cathode and the anode further comprisescarbon nanotubes.

570. The energy storage device of any one of embodiments 559 to 569,wherein at least one of the cathode and the anode further comprises aconductive filler.

571. The energy storage device of embodiment 570, wherein the conductivefiller comprises graphite.

572. The energy storage device of any one of embodiments 559 to 571,wherein at least one of the cathode and the anode further comprises anionic liquid.

573. The energy storage device of any one of embodiments 559 to 572,wherein at least one of the cathode and the anode further comprises abinder.

574. The energy storage device of any one of embodiments 559 to 573,further comprising a separator between the cathode and the anode.

575. The energy storage device of embodiment 574, wherein the separatorfurther comprises a third plurality of frustules.

576. The energy storage device of embodiment 575, wherein the thirdplurality of frustules comprises substantially no surface modifications.

577. The energy storage device of any one of embodiments 574 to 576,wherein the separator further comprises an electrolyte.

578. The energy storage device of embodiment 577, wherein theelectrolyte comprises the ionic liquid.

579. The energy storage device of embodiment 577 or 578, wherein theelectrolyte comprises the electrolyte salt.

580. The energy storage device of any one of embodiments 574 to 579,wherein the separator further comprises a polymer.

581. The energy storage device of any one of embodiments 559 to 580,further comprising a first current collector coupled to the cathode anda second current collector coupled to the anode.

582. The energy storage device of embodiment 581, wherein at least oneof the first current collector and the second current collectorcomprises a conductive foil.

583. The energy storage device of embodiment 582, wherein the conductivefoil comprises at least one of aluminum, copper, nickel, stainlesssteel, graphite, graphene and carbon nanotubes.

584. The energy storage device of embodiment 582 or 583, wherein atleast one of the first current collector and the second currentcollector comprises a printed current collector.

585. The energy storage device of embodiment 584, wherein the printedcurrent collector comprises at least one of aluminum, copper, nickel,silver, bismuth, conductive carbon, carbon nanotubes, graphene andgraphite.

586. A frustule comprising a plurality of nanostructures on at least onesurface, wherein the plurality of nanostructures comprises zinc oxide.

587. The frustule of embodiment 586, wherein the frustule comprisesabout 5 weight % to about 95 weight % of the plurality of nanostructurescomprising zinc oxide.

588. The frustule of embodiment 587, wherein the frustule comprisesabout 50 weight % to about 60 weight % of the nanostructures comprisingzinc oxide.

589. The frustule of any one of embodiments 586 to 588, wherein theplurality of nanostructures comprises at least one of nanowires,nanoplates, dense nanoparticles, nanobelts, and nanodisks.

590. A frustule comprising a plurality of nanostructures on at least onesurface, wherein the plurality of nanostructures comprises an oxide ofmanganese.

591. The frustule of embodiment 590, wherein the frustule comprisesabout 5 weight % to about 95 weight % of the plurality of nanostructurescomprising the oxide of manganese.

592. The frustule of embodiment 591, wherein the frustule comprisesabout 75 weight % to about 95 weight % of the plurality ofnanostructures comprising the oxide of manganese.

593. The frustule of any one of embodiments 590 to 592, wherein theoxide of manganese comprises MnO.

594. The frustule of any one of embodiments 590 to 593, wherein theoxide of manganese comprises Mn₃O_(4.)

595. The frustule of any one of embodiments 590 to 594, wherein theoxide of manganese comprises at least one of Mn₂O₃ and MnOOH.

596. The frustule of any one of embodiments 590 to 595, wherein theplurality of nanostructures comprises at least one of nanowires,nanoplates, dense nanoparticles, nanobelts, and nanodisks.

597. The frustule of any one of embodiments 590 to 596, wherein theplurality of nanostructures comprises at least one of nano-fibers andtetrahedral-shaped nanocrystals.

598. An electrode of an energy storage device, comprising:

a plurality of frustules, wherein each of the plurality of frustulescomprises a plurality of nanostructures formed on at least one surface.

599. The electrode of embodiment 598, wherein the electrode is an anodeof the energy storage device.

600. The electrode of embodiment 599, wherein the anode furthercomprises an electrolyte salt.

601. The electrode of embodiment 600, wherein the electrolyte saltcomprises a zinc salt.

602. The electrode of any one of embodiments 599 to 601, wherein theplurality of nanostructures comprises zinc oxide.

603. The electrode of any one of embodiments 599 to 602, wherein theplurality of nanostructures comprises at least one of nanowires,nanoplates, dense nanoparticles, nanobelts, and nanodisks.

604. The electrode of any one of embodiments 599 to 603, wherein atleast one of the plurality of frustules comprises about 5 weight % toabout 95 weight % of the plurality of nano structures.

605. The electrode of embodiment 604, wherein the at least one of theplurality of frustules comprises about 50 weight % to about 60 weight %of the plurality of nanostructures.

606. The electrode of embodiment 598, wherein the electrode is a cathodeof the energy storage device.

607. The electrode of embodiment 606, wherein the plurality ofnanostructures comprises an oxide of manganese.

608. The electrode of embodiment 607, wherein the oxide of manganesecomprises MnO.

609. The electrode of embodiment 607 or 608, wherein the oxide ofmanganese comprises Mn₃O_(4.)

610. The electrode of any one of embodiments 607 to 609, wherein theoxide of manganese comprises at least one of Mn₂O₃ and MnOOH.

611. The electrode of any one of embodiments 606 to 610, wherein theplurality of nanostructures comprises at least one of nanowires,nanoplates, dense nanoparticles, nanobelts, and nanodisks.

612. The electrode of any one of embodiments 606 to 611, wherein theplurality of nanostructures comprises at least one of nano-fibers andtetrahedral-shaped nanocrystals.

613. The electrode of any one of embodiments 606 to 611, wherein atleast one of the plurality of frustules comprises about 5 weight % toabout 95 weight % of the plurality of nano structures.

614. The electrode of embodiment 613, wherein the at least one of theplurality of frustules comprises about 75 weight % to about 95 weight %of the plurality of nano structures.

615. The electrode of any one of embodiments 598 to 614, wherein theelectrode further comprises carbon nanotubes.

616. The electrode of any one of embodiments 598 to 615, wherein theelectrode further comprises a conductive filler.

617. The electrode of embodiment 616, wherein the conductive fillercomprises graphite.

618. The electrode of any one of embodiments 598 to 617, wherein theelectrode further comprises an ionic liquid.

619. The electrode of any one of embodiments 598 to 618, wherein theelectrode further comprises a binder.

620. A method of forming zinc oxide nanostructures on a plurality offrustules, comprising:

-   -   providing the plurality of frustules;    -   forming a seed layer comprising zinc oxide on the plurality of        frustules to provide a plurality of zinc oxide seeded frustules;        and    -   forming nanostructures comprising zinc oxide on the seed layer        of the plurality of zinc oxide seeded frustules.

621. The method of embodiment 620, wherein forming the seed layercomprises providing a seed layer solution comprising about 2 weight % toabout 5 weight % of the plurality of frustules.

622. The method of embodiment 621, wherein the seed layer solutioncomprises about 0.1 weight % to about 0.5 weight % zinc salt.

623. The method of embodiment 622, wherein the zinc salt comprisesZn(CH₃COO)₂.

624. The method of any one of embodiments 621 to 623, wherein the seedlayer solution comprises about 94.5 weight % to about 97.9 weight % ofan alcohol.

625. The method of embodiment 624, wherein the alcohol comprisesethanol. 626. The method of any one of embodiments 621 to 625, furthercomprising heating the seed layer solution.

627. The method of embodiment 626, wherein heating the seed layersolution comprises heating the seed layer solution to a temperaturegreater than about 80° C.

628. The method of embodiment 626 or 627, wherein heating the seed layersolution comprises heating the seed layer solution in a vacuum oven.

629. The method of embodiment 628, wherein heating the seed layersolution in a vacuum oven comprises heating at a pressure of about 1millibar.

630. The method of any one of embodiments 621 to 629, further comprisingannealing the plurality of frustules.

631. The method of embodiment 631, wherein annealing comprises annealingat a temperature of about 200° C. to about 500° C.

632. The method of any one of embodiments 620 to 631, wherein formingthe zinc oxide nanostructures comprises forming a nanostructure solutioncomprising about 1 weight % to about 5 weight % of the plurality of zincoxide seeded frustules.

633. The method of embodiment 632, wherein the nanostructure solutioncomprises about 6 weight % to about 10 weight % of a zinc salt.

634. The method of embodiment 633, wherein the zinc salt comprisesZn(NO₃)₂.

635. The method of any one of embodiments 632 to 634, wherein thenanostructure solution comprises about 1 weight % to about 2 weight % ofa base.

636. The method of embodiment 635, wherein the base comprises ammoniumhydroxide (NH₄OH).

637. The method of any one of embodiments 632 to 636, wherein thenanostructure solution comprises about 1 weight % to about 5 weight % ofan additive.

638. The method of embodiment 637, wherein the additive compriseshexamethylenetetramine (HMTA).

639. The method of any one of embodiments 632 to 638, wherein thenanostructure solution comprises about 78 weight % to about 91 weight %purified water.

640. The method of any one of embodiments 632 to 638, wherein formingthe zinc oxide nanostructures comprises heating the nanostructuresolution.

641. The method of embodiment 640, wherein heating comprises heatingwith a microwave.

642. The method of embodiment 640 or 641, wherein heating comprisesheating to a temperature of about 100° C. to about 250° C.

643. The method of any one of embodiments 640 to 642, further comprisingstirring during heating.

644. The method of any one of embodiments 620 to 643, wherein at leastone of the plurality of frustules comprises about 5 weight % to about 95weight % of the zinc oxide.

645. A method of forming nanostructures comprising an oxide of manganeseon a plurality of frustules, comprising:

-   -   providing the plurality of frustules; and    -   forming the nanostructures comprising the oxide of manganese on        the plurality of frustules, wherein forming the nanostructures        comprises providing a solution comprising a manganese source for        forming the nanostructures comprising the oxide of manganese.

646. The method of embodiment 645, wherein the manganese sourcecomprises a manganese salt, and wherein the solution comprises about 7weight % to about 10 weight % of the manganese salt.

647. The method of embodiment 646, wherein the manganese salt comprisesmanganese acetate (Mn(CH₃COO)₂).

648. The method of any one of embodiments 645 to 647, wherein thesolution comprises about 0.5 weight % to about 2 weight % of theplurality of frustules.

649. The method of any one of embodiments 645 to 648, wherein thesolution comprises about 5 weight % to about 10 weight % of a base.

650. The method of embodiment 649, wherein the base comprises ammoniumhydroxide (NH₄OH).

651. The method of any one of embodiments 645 to 650, wherein thesolution comprises about 78 weight % to about 87.5 weight % ofoxygenated purified water.

652. The method of any one of embodiments 645 to 651, further comprisingheating the solution.

653. The method of embodiment 652, wherein heating comprises heatingwith microwave.

654. The method of embodiment 652 or 653, wherein heating the solutioncomprises heating to a temperature of about 100° C. to about 250° C.

655. The method of any one of embodiments 652 to 654, further comprisingstirring while heating.

656. An ink for an electrode of an energy storage device, comprising:

-   -   a plurality of frustules, wherein each of the plurality of        frustules comprises a plurality of nanostructures formed on a        surface; and    -   a polymer binder.

657. The ink of embodiment 656, wherein the electrode is an anode of theenergy storage device.

658. The ink of embodiment 657, wherein the plurality of nanostructurescomprises zinc oxide.

659. The ink of embodiment 657 or 658, wherein at least one of theplurality of frustules comprises about 5 weight % to about 95 weight %of the nanostructures.

660. The ink of any one of embodiments 657 to 659, further comprising anelectrolyte salt.

661. The ink of embodiment 660, wherein the electrolyte salt comprises azinc salt.

662. The ink of embodiment 661, wherein the zinc salt comprises zinctetrafluoroborate.

663. The ink of embodiment 656, wherein the electrode is a cathode ofthe energy storage device.

664. The ink of embodiment 663, wherein the plurality of nanostructurescomprises an oxide of manganese.

665. The ink of embodiment 664, wherein the oxide of manganese comprisesMnO.

666. The ink of embodiment 664 or 665, wherein the oxide of manganesecomprises Mn₃O_(4.)

667. The ink of any one of embodiments 663 to 666, wherein the oxide ofmanganese comprises at least one of Mn₂O₃ and MnOOH.

668. The ink of any one of embodiments 663 to 667, wherein at least oneof the plurality of frustules comprises about 5 weight % to about 95weight % of the nanostructures.

669. The ink of any one of embodiments of 656 to 668, further comprisingabout 10 weight % to about 20 weight % of the plurality of frustules.

670. The ink of any one of embodiments 656 to 669, further comprising anionic liquid.

671. The ink of embodiment 670, wherein the ink comprises about 2 weight% to about 15 weight % of the ionic liquid.

672. The ink of embodiment 670 or 671, wherein the ionic liquidcomprises 1-ethyl-3-ethylimidazolium tetrafluoroborate.

673. The ink of any one of embodiments of 656 to 672, further comprisinga conductive filler.

674. The ink of embodiment 673, further comprising up to about 10 weight% of the conductive filler.

675. The ink of embodiment 673 or 674, wherein the conductive fillercomprises graphite.

676. The ink of any one of embodiments of 656 to 675, further comprisingcarbon nanotubes.

677. The ink of embodiment 676, further comprising about 0.2 weight % toabout 20 weight % of the carbon nanotubes.

678. The ink of embodiment 676 or 677, wherein the carbon nanotubescomprises multi-wall carbon nanotubes.

679. The ink of any one of embodiments of 656 to 678, wherein the inkcomprises about 1 weight % to about 5 weight % of the polymer binder.

680. The ink of embodiment 679, wherein the polymer binder comprisespolyvinylidene fluoride.

681. The ink of any one of embodiments of 656 to 680, further comprisinga solvent.

682. The ink of embodiment 681, wherein the ink comprises about 47weight % to about 86.8 weight % of the solvent.

683. The ink of embodiment 681 or 682, wherein the solvent comprisesN-Methyl-2-pyrrolidone.

684. A method of preparing an ink for an electrode of an energy storagedevice, the method comprising:

-   -   providing an ionic liquid;    -   dispersing a plurality of carbon nanotubes in the ionic liquid        to form a first dispersion comprising the plurality of carbon        nanotubes and the ionic liquid; and    -   adding a plurality of frustules, wherein each of the plurality        of frustules comprises a plurality of nanostructures on a        surface.

685. The method of embodiment 684, wherein the plurality ofnanostructures comprises zinc oxide.

686. The method of embodiment 684, wherein the plurality ofnanostructures comprises an oxide of manganese.

687. The method of embodiment 686, wherein the oxide of manganesecomprises MnO.

688. The method of embodiment 686 or 687, wherein the oxide of manganesecomprises Mn₃O_(4.)

689. The method of any one of embodiments 686 to 688, wherein the oxideof manganese comprises at least one of Mn₂O₃ and MnOOH.

690. The method of any one of embodiments 684 to 689, further comprisingforming a second dispersion comprising the plurality of carbonnanotubes, the ionic liquid and a solvent.

691. The method of embodiment 690, wherein the solvent comprisesN-Methyl-2-pyrrolidone.

692. The method of embodiment 690 or 691, wherein adding the pluralityof frustules comprises adding the plurality of frustules to the seconddispersion to form a first mixture.

693. The method of embodiment 692, further comprising adding aconductive filler to the second dispersion to form the first mixture.

694. The method of embodiment 693, wherein the conductive fillercomprises graphite.

695. The method of embodiment 692 or 693, further comprising adding anelectrolyte salt to the first mixture to form a second mixture.

696. The method of embodiment 695, wherein the electrolyte saltcomprises a zinc salt.

697. The method of embodiment 696, wherein the zinc salt comprises zinctetrafluoroborate.

698. The method of any one of embodiments 695 to 697, wherein at leastone of adding the plurality of frustules, the conductive filler and theelectrolyte salt comprises stirring.

699. The method of embodiment 698, wherein stirring comprises applying acentrifugal mixer.

700. The method of any one of embodiments 695 to 699, further comprisingadding a solution to the second mixture to form a third mixture, whereinthe solution comprises the solvent and a polymer binder.

701. The method of embodiment 700, wherein the polymer binder is about10 weight % to about 20 weight % of the solution.

702. The method of embodiment 700 or 701, wherein the polymer bindercomprises polyvinylidene fluoride.

703. The method of any one of embodiments 700 to 702, further comprisingheating the third mixture.

704. The method of embodiment 703, wherein the heating comprises heatingto a temperature of about 80° C. to about 180° C.

705. The method of embodiment 703 or 704, further comprising stirringduring the heating.

706. A method of printing an energy storage device, comprising:

-   -   printing a first electrode comprising a first plurality of        frustules, wherein each of the plurality of frustules comprises        a first plurality of nanostructures on a surface; and    -   printing a separator over the first electrode.

707. The method of embodiment 706, further comprising providing a firstcurrent collector, and wherein printing the first electrode comprisesprinting the first electrode over the first current collector.

708. The method of embodiment 707, wherein providing the first currentcollector comprises providing a first conductive foil.

709. The method of any one of embodiments 706 to 708, further comprisingproviding a second current collector.

710. The method of embodiment 709, wherein providing the second currentcollector comprises providing a second conductive foil.

711. The method of embodiment 710, further comprising printing a secondelectrode, wherein the second electrode comprises a second plurality offrustules, wherein each of the second plurality of frustules comprises asecond plurality of nanostructures on a surface.

712. The method of embodiment 711, wherein printing the second electrodecomprises printing the second electrode over the separator.

713. The method of embodiment 711, wherein printing the second electrodecomprises printing the second electrode over the second currentcollector.

714. The method embodiment 713, further comprising printing theseparator over the second electrode.

715. The method of embodiment 707, wherein providing the first currentcollector comprises printing the first current collector.

716. The method of embodiment 715, further comprising printing a secondelectrode over the separator, wherein the second electrode comprises asecond plurality of frustules, wherein each of the second plurality offrustules comprises a second plurality of nanostructures on a surface.

717. The method of embodiment 716, further comprising printing a secondcurrent collector over the second electrode.

718. The method of embodiment 715, wherein further comprising printing asecond current collector at a lateral distance from the first currentcollector.

719. The method of embodiment 718, further comprising printing a secondelectrode over the second current collector at the lateral distance fromthe first current collector, wherein the second electrode comprises asecond plurality of frustules, wherein each of the second plurality offrustules comprises a second plurality of nanostructures on a surface.

720. The method of embodiment 719, wherein printing the separatorcomprises printing the separator over the first electrode and the secondelectrode.

721. A method of fabricating an energy storage device, comprising:

-   -   forming a first structure, wherein forming the first structure        comprises:        -   printing a first electrode over a first current collector,            and        -   printing a separator over the first electrode;    -   forming a second structure, wherein forming the second structure        comprises:        -   printing a second electrode over a second current collector;            and    -   coupling the first structure to the second structure to form the        energy storage device,    -   wherein coupling comprises providing the separator between the        first electrode and the second electrode.

722. A method of fabricating an energy storage device, comprising:

-   -   forming a first structure, wherein forming the first structure        comprises:        -   printing a first electrode over a first current collector,            and        -   printing a first portion of a separator over the first            electrode;    -   forming a second structure, wherein forming the second structure        comprises:        -   printing a second electrode over a second current collector,            and        -   printing a second portion of the separator over the second            electrode;    -   and    -   coupling the first structure to the second structure to form the        energy storage device,    -   wherein coupling comprises providing the first portion of the        separator and the second portion of the separator between the        first electrode and the second electrode.

723. A method of fabricating an energy storage device, comprising:

-   -   forming a first structure, wherein forming the first structure        comprises:        -   printing a first electrode over a first current collector,        -   printing a separator over the first electrode, and        -   printing a second electrode on the separator;    -   forming a second structure, wherein forming the second structure        comprises providing a second current collector; and    -   coupling the first structure to the second structure to form the        energy storage device,    -   wherein coupling comprises providing the second electrode        between the second current collector and the separator.

724. The method of any one of Embodiments 721-723, wherein the firstcurrent collector comprises a conductive foil.

725. The method of any one of Embodiments 721-723, further comprisingforming the first current collector on a substrate.

726. The method of Embodiment 725, wherein forming the first currentcollector comprises printing the first current collector over thesubstrate.

727. The method of any one of Embodiments 721-726, wherein the secondcurrent collector comprises a conductive foil.

728. The method of any one of Embodiments 721-726, further comprisingforming the second current collector on a second substrate.

729. The method of Embodiment 728, wherein forming the first currentcollector comprises printing the first current collector over the secondsubstrate.

730. A method of fabricating an energy storage device, comprising:

-   -   printing a first current collector;    -   printing a first electrode over the first current collector;    -   printing a separator over the first electrode;    -   printing a second electrode over the separator; and    -   printing a second current collector over the second electrode.

731. A method of fabricating an energy storage device, comprising:

-   -   printing a first current collector;    -   printing a second current collector at a lateral distance from        the first current collector;    -   printing a first electrode over the first current collector;    -   printing a second electrode over the second current collector;        and    -   printing a separator over the first electrode and the second        electrode and between the first electrode and the second        electrode.

732. The method of any one of embodiments 721 to 731, wherein the firstelectrode comprises a first plurality of frustules, wherein each of thefirst plurality of frustules comprises nanostructures formed on at leastone surface.

733. The method of embodiment 732, wherein the nanostructures comprisean oxide of manganese

734. The method of embodiment 733, wherein the oxide of manganesecomprises MnO.

735. The method of embodiment 733 or 734, wherein the oxide of manganesecomprises Mn₃O₄.

736. The method of any one of embodiments 733 to 735, wherein the oxideof manganese comprises at least one of Mn₂O₃ and MnOOH.

737. The method of any one of embodiments 721 to 736, wherein the secondelectrode comprises a second plurality of frustules, wherein each of thesecond plurality of frustules comprises nano structures.

738. The method of embodiment 737, wherein the nanostructures comprisezinc oxide.

739. The method of any one of embodiments 721 to 738, wherein theseparator comprises a third plurality of frustules, wherein each of thethird plurality of frustules comprises substantially no surfacemodifications.

740. An energy storage device comprising:

-   -   a cathode comprising a first plurality of frustules, the first        plurality of frustules comprises nano structures comprising an        oxide of manganese; and    -   an anode comprising a second plurality of frustules, the second        plurality of frustules comprises nanostructures comprising zinc        oxide.

741. The energy storage device of embodiment 740, wherein the oxide ofmanganese comprises MnO.

742. The energy storage device of embodiment 740 or 741, wherein theoxide of manganese comprises at least one of Mn₃O₄, Mn₂O₃, and MnOOH.

743. The energy storage device of any one of embodiments 740 to 742,wherein at least one of the first plurality of frustules comprises aratio of a mass of the oxide of manganese to a mass of the at least onefrustule of about 1:20 to about 20:1.

744. The energy storage device of any one of embodiments 740 to 743,wherein at least one of the second plurality of frustules comprises aratio of a mass of the zinc oxide to a mass of the at least one frustuleof about 1:20 to about 20:1.

745. The energy storage device of any one of embodiments 740 to 744,wherein the anode further comprises an electrolyte salt.

746. The energy storage device of embodiment 745, wherein theelectrolyte salt comprises a zinc salt.

747. The energy storage device of any one of embodiments 740 to 746,wherein at least one of the cathode and the anode further comprisescarbon nanotubes.

748. The energy storage device of any one of embodiments 740 to 747,wherein at least one of the cathode and the anode further comprises aconductive filler.

749. The energy storage device of embodiment 748, wherein the conductivefiller comprises graphite.

750. The energy storage device of any one of embodiments 740 to 749,further comprising a separator between the cathode and the anode,wherein the separator comprises a third plurality of frustules.

751. The energy storage device of embodiment 750, wherein the thirdplurality of frustules comprises substantially no surface modifications.

752. The energy storage device of embodiment 750 or 751, wherein atleast one of the cathode, the anode, and the separator comprises anionic liquid.

753. The energy storage device of any one of embodiments 740 to 752,wherein the device is a rechargeable battery.

754. The energy storage device of any one of embodiments 740 to 753,wherein the first plurality of frustules comprises a first plurality ofpores substantially not occluded by the nanostructures comprising theoxide of manganese, and wherein the second plurality of frustulescomprises a second plurality of pores substantially not occluded by thenanostructures comprising the zinc oxide.

755. A frustule comprising a plurality of nanostructures on at least onesurface, wherein the plurality of nanostructures comprises zinc oxide,wherein a ratio of a mass of the plurality of nanostructures to a massof the frustule is about 1:1 to about 20:1.

756. The frustule of embodiment 755, wherein the plurality ofnanostructures comprises at least one of nanowires, nanoplates, densenanoparticles, nanobelts, and nanodisks.

757. The frustule of embodiment 755 or 756, wherein the frustulecomprises a plurality of pores substantially not occluded by theplurality of nanostructures.

758. A frustule comprising a plurality of nanostructures on at least onesurface, wherein the plurality of nanostructures comprises an oxide ofmanganese, wherein a ratio of a mass of the plurality of nanostructuresto a mass of the frustule is about 1:1 to about 20:1.

759. The frustule of embodiment 758, wherein the oxide of manganesecomprises MnO.

760. The frustule of embodiment 758 or 759, wherein the oxide ofmanganese comprises Mn₃O_(4.)

761. The frustule of any one of embodiments 758 to 760, wherein theoxide of manganese comprises at least one of Mn₂O₃ and MnOOH.

762. The frustule of any one of embodiments 758 to 761, wherein theplurality of nanostructures comprises at least one of nanowires,nanoplates, dense nanoparticles, nanobelts, and nanodisks.

763. The frustule of any one of embodiments 758 to 762, wherein thefrustule comprises a plurality of pores substantially not occluded bythe plurality of nanostructures.

764. An electrode of an energy storage device, the electrode comprising:

-   -   a plurality of frustules, wherein each of the plurality of        frustules comprises a plurality of nanostructures formed on at        least one surface, wherein at least one of the plurality of        frustules comprises a ratio of a mass of the plurality of        nanostructures to a mass of the at least one frustule of 1:20 to        20:1.

765. The electrode of embodiment 764, wherein the electrode is an anodeof the energy storage device.

766. The electrode of embodiment 765, wherein the anode furthercomprises an electrolyte salt.

767. The electrode of embodiment 766, wherein the electrolyte saltcomprises a zinc salt.

768. The electrode of any one of embodiments 765 to 767, wherein theplurality of nanostructures comprises zinc oxide.

769. The electrode of any one of embodiments 764 to 768, wherein theplurality of nanostructures comprises at least one of nanowires,nanoplates, dense nanoparticles, nanobelts, and nanodisks.

770. The electrode of embodiment 764 or 769, wherein the electrode is acathode of the energy storage device.

771. The electrode of embodiment 770, wherein the plurality ofnanostructures comprises an oxide of manganese.

772. The electrode of embodiment 771, wherein the oxide of manganesecomprises MnO.

773. The electrode of embodiment 771 or 772, wherein the oxide ofmanganese comprises at least one of Mn₃O₄, Mn₂O₃ and MnOOH.

774. The electrode of any one of embodiments 764 to 773, furthercomprising carbon nanotubes.

775. The electrode of any one of embodiments 764 to 774, furthercomprising a conductive filler.

776. The electrode of embodiment 775, wherein the conductive fillercomprises graphite.

777. The electrode of any one of embodiments 764 to 776, furthercomprising an ionic liquid.

778. The electrode of any one of embodiments 764 to 777, wherein each ofthe plurality of frustules comprises a plurality of pores substantiallynot occluded by the plurality of nanostructures.

779. The energy storage device of any one of embodiments 559 to 562 and565 to 585, wherein a mass of the nanostructures comprising the oxide ofmanganese of at least one frustule of the first plurality of frustulesto a mass of the at least one frustule is about 1:20 to about 100:1.

780. The energy storage device of embodiment 779, wherein the mass ofthe nanostructures comprising the oxide of manganese of at least onefrustule of the first plurality of frustules to the mass of the at leastone frustule is about 1:1 to about 100:1.

781. The energy storage device of embodiment 779, wherein the mass ofthe nanostructures comprising the oxide of manganese of at least onefrustule of the first plurality of frustules to the mass of the at leastone frustule is about 1:20 to about 100:1.

782. The energy storage device of any one of embodiments 559 to 564, 567to 585 and 779 to 781, wherein a mass of the ZnO of at least onefrustule of the second plurality of frustules to a mass of the at leastone frustule of the second plurality of frustules is about 1:20 to about100:1.

783. The energy storage device embodiment 782, wherein the mass of theZnO of at least one frustule of the second plurality of frustules to themass of the at least one frustule of the second plurality of frustulesis about 1:1 to about 100:1.

784. The energy storage device embodiment 782, wherein the mass of theZnO of at least one frustule of the second plurality of frustules to themass of the at least one frustule of the second plurality of frustulesis about 20:1 to about 100:1.

785. The frustule of any one of embodiments 586 and 589, wherein a massof the ZnO to a mass of the frustule is about 1:20 to about 100:1.

786. The frustule of embodiment 785, wherein the mass of the ZnO to themass of the frustule is about 1:1 to about 100:1.

787. The frustule of embodiment 785, wherein the mass of the ZnO to themass of the frustule is about 20:1 to about 100:1.

788. The frustule of any one of embodiments 590 and 593 to 597, whereina mass of the plurality of nanostructures comprising the oxide ofmanganese to a mass of the frustule is about 1:20 to about 100:1.

789. The frustule of embodiment 788, wherein the mass of the pluralityof nanostructures comprising the oxide of manganese to the mass of thefrustule is about 1:1 to about 100:1.

790. The frustule of embodiment 788, wherein the mass of the pluralityof nanostructures comprising the oxide of manganese to the mass of thefrustule is about 20:1 to about 100:1.

791. The electrode of any one of embodiments 598 to 603 and 606 to 612,615 to 619, wherein a mass of the plurality of nanostructures to a massof at least one frustule of the plurality of frustules is about 1:20 toabout 100:1.

792. The electrode of embodiment 791, wherein the mass of the pluralityof nanostructures to the mass of the at least one frustule is about 1:1to about 100:1.

793. The electrode of embodiment 791, wherein the mass of the pluralityof nanostructures to the mass of the at least one frustule is about 20:1to about 100:1.

794. The method of any one of embodiments 620 to 643, wherein a mass ofthe zinc oxide to a mass of at least one frustule of the plurality offrustules is about 1:20 to about 100:1.

795. The method of embodiment 794, wherein the mass of the zinc oxide tothe mass of the at least one frustule is about 1:1 to about 100:1.

796. The method of embodiment 794, wherein the mass of the zinc oxide tothe mass of the at least one frustule is about 20:1 to about 100:1.

797. The method of any one of embodiments 645 to 655, wherein a mass ofthe nanostructures comprising the oxide of manganese to a mass of atleast one frustule of the plurality of frustules is about 1:20 to about100:1.

798. The method of embodiment 797, wherein the mass of thenanostructures comprising the oxide of manganese to the mass of the atleast one frustule is about 1:1 to about 100:1.

799. The method of embodiment 797, wherein the mass of thenanostructures comprising the oxide of manganese to the mass of the atleast one frustule is about 20:1 to about 100:1.

800. The ink of any one of embodiments 656 to 658, 660 to 667 and 669 to683, wherein a mass of the plurality of nanostructures to a mass of atleast one frustule of the plurality of frustules is about 1:20 to about100:1.

801. The ink of embodiment 800, wherein the mass of the plurality ofnanostructures to the mass of the at least one frustule is about 1:1 toabout 100:1.

802. The ink of embodiment 800, wherein a mass of the plurality ofnanostructures to the mass of the at least one frustule is about 20:1 toabout 100:1.

803. A supercapacitor comprising a pair of electrodes and an electrolytecomprising an ionic liquid, wherein at least one of the electrodescomprises a plurality of frustules having formed thereon a surfaceactive material.

804. The super capacitor of embodiment 803, wherein each of theplurality of frustules is coated with the surface active material.

805. The supercapacitor of embodiments 803 or 804, wherein a first oneof the electrodes comprises the frustules.

806. The supercapacitor of any one of embodiments 803 to 805, whereineach of the pair of electrodes comprises the frustules.

807. The supercapacitor of any one of embodiments 803 to 806, wherein noion transport occurs from one electrode to the other as part of anelectrochemical reaction during charge or discharge.

808. The supercapacitor of any one of embodiments 803 to 807, whereinthe supercapacitor is configured to be charged to have a voltagedifference between the electrodes that exceeds 2 volts.

809. The supercapacitor of any one of embodiments 803 to 808, whereinthe ionic liquid comprises a molten salt.

810. The supercapacitor of any one of embodiments 803 to 809, whereinthe surface active material comprises nanostructures formed on surfacesof the frustules.

811. The supercapacitor of any one of embodiments 803 to 810, whereinthe surface active material comprises nanostructures coveringsubstantially all surfaces of the frustules.

812. The supercapacitor of any one of embodiments 803 to 811, wherein atleast one of the electrodes is configured substantially as one or bothof an electric double layer capacitor and a pseudo capacitor.

813. The supercapacitor of any one of embodiments 803 to 812, wherein atleast one of the electrodes is configured substantially as one of anelectric double layer capacitor or a pseudo capacitor while not beingconfigured substantially as the other of the double layer capacitor orthe pseudo capacitor.

814. The supercapacitor of any one of embodiments 803 to 813, whereinupon application of a voltage across the electrodes, a first sheet ofcharge of first polarity forms at surfaces of the surface activematerial of the at least one of the electrodes configured as an electricdouble layer capacitor, and a second sheet of charge of second polarityforms adjacent to the at least one of the electrodes configured as thedouble layer capacitor, wherein the first and second sheets of chargeare interposed by a layer of the electrolyte.

815. The supercapacitor of any one of embodiments 803 to 814, whereinupon application of a voltage across the electrodes, the at least one ofthe electrodes configured as a pseudo capacitor stores energy by areversible Faradaic redox reaction on the surface of the surface activematerial.

816. The supercapacitor of any one of embodiments 803 to 815, whereinthe surface active material of at least one of the electrodes comprisescarbon nanotubes (CNTs).

817. The supercapacitor of embodiment 816, wherein the surface activematerial of each of the pair of the electrodes comprises the CNTs.

818. The supercapacitor of embodiments 816 or 817, wherein the surfaceactive material comprises the CNTs formed on a surface of each of thefrustules.

819. The supercapacitor of any one of embodiments 816 to 818, whereinthe at least one of the electrodes comprising the CNTs are configuredsubstantially as an electric double layer capacitor.

820. The supercapacitor of any one of embodiments 803 to 815, whereinthe surface active material of at least one of the electrodes comprisesone or both of a zinc oxide and a manganese oxide.

821. The supercapacitor of embodiment 820, wherein the surface activematerial of the at least one of the electrodes comprises one or both ofzinc oxide nanoparticles and manganese oxide nanoparticles.

822. The supercapacitor of embodiments 820 or 821, wherein the surfaceactive material of the at least one of the electrodes comprises one orboth of the zinc oxide nanoparticles and the manganese oxidenanoparticle formed on a surface of each of the fru stules.

823. The supercapacitor of any one of embodiments 820 to 822, whereinthe surface active material of each of the pair of the electrodescomprises one or both of the zinc oxide and the manganese oxide.

824. The supercapacitor of any one of embodiments 820 to 823, whereinthe at least one of the electrodes comprising one or both of the zincoxide and the manganese oxide are configured substantially as a pseudocapacitor.

825. The supercapacitor of any one of embodiments 803 to 815, whereinthe surface active material of at least one of the electrodes comprisesone but not the other of the zinc oxide and the manganese oxide.

826. The supercapacitor of any one of embodiments 820 to 825, whereinthe manganese oxide comprises one or more of manganese dioxide (MnO₂),manganese(II, III) oxide (Mn₃O₄), manganese(II) oxide (MnO),manganese(III) oxide (Mn₂O₃).

827. The supercapacitor of any one of embodiments 816 to 826, whereinthe surface active material of one of the pair of electrodes comprisesCNTs and the surface active material of the other of pair of electrodescomprises one or both of the zinc oxide and the manganese oxide.

828. The supercapacitor of any one of embodiments 803 to 827, whereinthe ionic liquid comprises one or more cations selected from the groupconsisting of butyltrimethylammonium, 1-ethyl-3-methylimidazolium,1-butyl-3-methylimidazolium, 1-methyl-3-propylimidazolium,1-hexyl-3-methylimidazolium, choline, ethylammonium,tributylmethylphosphonium, tributyl(tetradecyl)phosphonium,trihexyl(tetradecyl)phosphonium, 1-ethyl-2,3-methylimidazolium,1-butyl-1-methylpiperidinium, diethylmethylsulfonium,1-methyl-3-propylimidazolium, 1-ethyl-3-methylimidazolium,1-methyl-1-propylpiperidinium, 1-butyl-2-methylpyridinium,1-butyl-4-methylpyridinium, 1-butyl-1-methylpyrrolidinium,diethylmethylsulfonium and combinations thereof.

829. The supercapacitor of any one of embodiments 803 to 828, whereinthe ionic liquid comprises or more anions selected from the groupconsisting of tris(pentafluoroethyl)trifluorophosphate,trifluoromethanesulfonate, hexafluorophosphate, tetrafluoroborate, ethylsulfate, dimethyl phosphate, methansulfonate, triflate,tricyanomethanide, dibutylphosphate, bis(trifluoromethylsulfonyl)imide,bis-2,4,4-(trimethylpentyl) phosphinate, iodide, chloride, bromide,nitrate and combinations thereof.

830. The supercapacitor of any one of embodiments 803 to 829, whereinthe ionic liquid comprises 1-ethyl-3-methylimidazolium tetrafluoroborate(C₂mimBF₄).

831. The supercapacitor of any one of embodiments 803 to 830, whereinthe electrolyte further comprises a salt dissolved therein.

832. The supercapacitor of embodiment 831, wherein the salt has at leasta cation that is different from a cation of the ionic liquid.

833. The supercapacitor of embodiments 831 or 832, wherein the saltcomprises a cation selected from a group consisting of zinc, sodium,potassium, magnesium, calcium, aluminum, lithium, barium andcombinations thereof.

834. The supercapacitor of any one of embodiments 831 to 833, whereinthe salt comprises at least an anion that is different from an anion ofthe ionic liquid.

835. The supercapacitor of any one of embodiments 831 to 834, whereinthe salt comprises an anion selected from the group consisting ofchloride, bromide, fluoride, bis(trifluoromethanesulfonyl)imide,sulfate, bisulfite, nitrate, nitrite, carbonate, hydroxide, perchloride,bicarbonate, tetrafluoroborate, methansulfonate, acetate, phosphate,citrate, hexafluorophosphate and combinations thereof.

836. The supercapacitor of any one of embodiments 831 to 835, whereinthe salt comprises an organic salt.

837. The supercapacitor of any one of embodiments 831 to 836, whereinthe salt comprises an anion selected from the group consisting oftetraethylammonium tetrafluoroborate, tetraethylammoniumdifluoro(oxalate)borate, methylammonium tetrafluoroborate,triethylmethylammonium tetrafluoroborate, tetrafluoroboric aciddimethyldi ethylammonium, triethylmethylammonium tetrafluoroborate,tetrapropylammonium tetrafluoroborate, methyltributylammoniumtetrafluoroborate, tetrabutylammonium tetrafluoroborate,tetrahexylammonium tetrafluoroborate, tetramethylammoniumtetrafluoroborate, tetraethyl phosphonium tetrafluoroborate,tetrapropylphosphonium tetrafluoroborate, tetrabutylphosphonium,tetrafluoroborate and combinations thereof.

838. The supercapacitor of any one of embodiments 831 to 836, whereinthe salt comprises an inorganic salt.

839. The supercapacitor of embodiment 838, wherein the inorganic saltcomprises a salt selected from the group consisting of LiCl; Li₂SO₄,LiClO₄, NaCl, Na₂SO₄, NaNO₃, KCl, K₂SO₄, KNO₃, Ca(NO₃)₂, MgSO₄ andcombinations thereof.

840. The supercapacitor of any one of embodiments 803 to 839, whereinthe electrolyte comprises an acid selected from the group consisting ofH₂SO₄, HCl, HNO₃, HClO₄ and combinations thereof.

841. The supercapacitor of any one of embodiments 803 to 839, whereinthe electrolyte comprises a base selected from the group consisting ofKOH, NaOH, LiOH, NH₄OH and combinations thereof.

842. The supercapacitor of any one of embodiments 831 to 833 and 835 to841, wherein the salt comprises the same anion as an anion of the ionicliquid.

843. The supercapacitor of embodiment 838, wherein the salt compriseszinc tetrafluoroborate Zn(BF₄)₂.

844. The supercapacitor of any one of embodiments 803 to 843, furthercomprising a separator interposed between the pair of electrodes.

845. The supercapacitor of embodiment 844, wherein the separatorcomprises a plurality of frustules.

846. The supercapacitor of embodiment 845, wherein the separator furthercomprises graphene oxide.

847. The supercapacitor of any one of embodiments 803 to 846, whereinthe frustules comprise chemically unmodified frustules.

848. A supercapacitor comprising a pair of electrodes contacting anelectrolyte, wherein at least one of the electrodes comprise a pluralityof frustules and a zinc oxide.

849. The supercapacitor of embodiment 848, wherein each of the frustulesis coated with the zinc oxide.

850. The supercapacitor of embodiments 848 or 849, wherein each of thefrustules is coated with nanostructures comprising the zinc oxide.

851. The supercapacitor of any one of embodiments 848 to 850, whereinone or both of the electrodes further comprise carbon nanotubes (CNTs).

852. The supercapacitor of embodiment 848, wherein one of the electrodescomprises the zinc oxide and the other of the electrodes comprisescarbon nanotubes (CNTs).

853. The supercapacitor of embodiments 851 or 852, wherein each of thefrustules are coated with the CNTs.

854. The supercapacitor of any one of embodiments 848 to 853, whereinthe electrolyte comprises an aqueous electrolyte.

855. The supercapacitor of any one of embodiments 848 to 853, whereinthe electrolyte comprises a non-aqueous electrolyte.

856. The supercapacitor of any one of embodiments 848 to 855, wherein noion transport occurs from one electrode to the other as part of anelectrochemical reaction during charge or discharge.

857. The supercapacitor of any one of embodiments 848 to 856, wherein atleast one of the electrodes is configured substantially as one or bothof an electric double layer capacitor and a pseudo capacitor.

858. The supercapacitor of any one of embodiments 848 to 857, wherein atleast one of the electrodes is configured substantially as one of anelectric double layer capacitor or a pseudo capacitor while not beingconfigured substantially as the other of the double layer capacitor orthe pseudo capacitor.

859. The supercapacitor of any one of embodiments 848 to 858, whereinupon application of a voltage across the electrodes, a first sheet ofcharge of first polarity forms at surfaces of the surface activematerial of the at least one of the electrodes configured as an electricdouble layer capacitor, and a second sheet of charge of second polarityforms adjacent to the at least one of the electrodes configured as thedouble layer capacitor, wherein the first and second sheets of chargeare interposed by a layer of electrolyte.

860. The supercapacitor of any one of embodiments 848 to 859, whereinupon application of a voltage across the electrodes, the at least one ofthe electrodes configured as a pseudo capacitor stores energy by areversible Faradaic redox reaction on the surface of the surface activematerial.

861. The supercapacitor of any one of embodiments 848 to 860, whereinthe at least one of the electrodes comprising the zinc oxide areconfigured substantially as a pseudo capacitor.

862. The supercapacitor of any one of embodiments 848 to 861, whereinthe at least one of the electrodes comprising the CNTs are configuredsubstantially as an electric double layer capacitor.

863. The supercapacitor of any one of embodiments 848 to 861, whereinthe electrolyte comprises an ionic liquid.

864. The supercapacitor of any one of embodiments 848 to 863, whereinthe ionic liquid comprises one or more cations selected from the groupconsisting of butyltrimethylammonium, 1-ethyl-3-methylimidazolium,1-butyl-3-methylimidazolium, 1-methyl-3-propylimidazolium,1-hexyl-3-methylimidazolium, choline, ethylammonium,tributylmethylphosphonium, tributyl(tetradecyl)phosphonium,trihexyl(tetradecyl)phosphonium, 1-ethyl-2,3-methylimidazolium,1-butyl-1-methylpiperidinium, diethylmethylsulfonium,1-methyl-3-propylimidazolium, 1-ethyl-3-methylimidazolium,1-methyl-1-propylpiperidinium, 1-butyl-2-methylpyridinium,1-butyl-4-methylpyridinium, 1-butyl-1-methylpyrrolidinium,diethylmethylsulfonium and combinations thereof.

865. The supercapacitor of any one of embodiments 848 to 864, whereinthe ionic liquid comprises or more anions selected from the groupconsisting of tris(pentafluoroethyl)trifluorophosphate,trifluoromethanesulfonate, hexafluorophosphate, tetrafluoroborate, ethylsulfate, dimethyl phosphate, methansulfonate, triflate,tricyanomethanide, dibutylphosphate, bis(trifluoromethylsulfonyl)imide,bis-2,4,4-(trimethylpentyl) phosphinate, iodide, chloride, bromide,nitrate and combinations thereof.

866. The supercapacitor of any one of embodiments 848 to 865, whereinthe ionic liquid comprises 1-ethyl-3-methylimidazolium tetrafluoroborate(C₂mimBF₄).

867. The supercapacitor of any one of embodiments 848 to 866, whereinthe electrolyte further comprises a salt dissolved therein.

868. The supercapacitor of embodiment 867, wherein the salt has at leasta cation that is different from a cation of the ionic liquid.

869. The supercapacitor of embodiments 867 or 868, wherein the saltcomprises a cation selected from a group consisting of zinc, sodium,potassium, magnesium, calcium, aluminum, lithium, barium andcombinations thereof.

870. The supercapacitor of any one of embodiments 867 to 869, whereinthe salt comprises at least an anion that is different from an anion ofthe ionic liquid.

871. The supercapacitor of any one of embodiments 867 to 870, whereinthe salt comprises an anion selected from the group consisting ofchloride, bromide, fluoride, bis(trifluoromethanesulfonyl)imide,sulfate, bisulfite, nitrate, nitrite, carbonate, hydroxide, perchloride,bicarbonate, tetrafluoroborate, methansulfonate, acetate, phosphate,citrate, hexafluorophosphate and combinations thereof.

872. The supercapacitor of any one of embodiments 867 to 871, whereinthe salt comprises an organic salt.

873. The super capacitor of any one of embodiments 867 to 872, whereinthe salt comprises an anion selected from the group consisting oftetraethylammonium tetrafluoroborate, tetraethylammoniumdifluoro(oxalate)borate, methylammonium tetrafluoroborate,triethylmethylammonium tetrafluoroborate, tetrafluoroboric aciddimethyldi ethylammonium, triethylmethylammonium tetrafluoroborate,tetrapropylammonium tetrafluoroborate, methyltributylammoniumtetrafluoroborate, tetrabutylammonium tetrafluoroborate,tetrahexylammonium tetrafluoroborate, tetramethylammoniumtetrafluoroborate, tetraethyl phosphonium tetrafluoroborate,tetrapropylphosphonium tetrafluoroborate, tetrabutylphosphonium,tetrafluoroborate and combinations thereof.

874. The supercapacitor of any one of embodiments 867 to 871, whereinthe salt comprises an inorganic salt.

875. The supercapacitor of embodiment 874, wherein the inorganic saltcomprises a salt selected from the group consisting of LiCl; Li₂SO₄,LiClO₄, NaCl, Na₂SO₄, NaNO₃, KCl, K₂SO₄, KNO₃, Ca(NO₃)₂, MgSO₄ andcombinations thereof.

876. The supercapacitor of any one of embodiments 848 to 874, whereinthe electrolyte comprises an acid selected from the group consisting ofH₂SO₄, HCl, HNO₃, HClO₄ and combinations thereof.

877. The supercapacitor of any one of embodiments 848 to 874, whereinthe electrolyte comprises a base selected from the group consisting ofKOH, NaOH, LiOH, NH₄OH and combinations thereof.

878. The supercapacitor of any one of embodiments 867 to 869 and 870 to877, wherein the salt comprises the same anion as an anion of the ionicliquid.

879. The supercapacitor of embodiment 878, wherein the salt compriseszinc tetrafluoroborate Zn(BF₄)₂.

880. The supercapacitor of any one of embodiments 848 to 879, furthercomprising a separator interposed between the pair of electrodes.

881. The supercapacitor of embodiment 880, wherein the separatorcomprises a plurality of frustules.

882. The supercapacitor of embodiment 881, wherein the separator furthercomprises graphene oxide.

883. The supercapacitor of any one of embodiments 848 to 882, whereinthe frustules comprise chemically unmodified frustules.

884. A supercapacitor comprising a pair of electrodes contacting anon-aqueous electrolyte, wherein at least one of the electrodes comprisea plurality of frustules and a manganese oxide.

885. The supercapacitor of embodiment 884, wherein each of the frustulesare coated with the manganese oxide.

886. The supercapacitor of embodiments 884 or 885, wherein each of thefrustules are coated with nanostructures comprising the manganese oxide.

887. The supercapacitor of any one of embodiments 884 to 886, whereinthe at least one of the electrodes further comprise zinc oxide.

888. The supercapacitor of any one of embodiments 884 to 887, whereineach of the frustules are coated with the zinc oxide.

889. The supercapacitor of any one of embodiments 884 to 888, whereineach of the frustules are coated with nanostructures comprising the zincoxide.

890. The supercapacitor of any one of embodiments 884 to 889, whereinone or both of the electrodes further comprise carbon nanotubes (CNTs).

891. The supercapacitor of embodiment 884, wherein one of the electrodescomprises the manganese oxide and the other of the electrodes comprisescarbon nanotubes (CNTs).

892. The supercapacitor of embodiments 890 or 891, wherein each of thefrustules are coated with the CNTs.

893. The supercapacitor of any one of embodiments 884 to 892, whereinthe manganese oxide comprises one or more of manganese dioxide (MnO₂),manganese(II, III) oxide (Mn₃O₄), manganese(II) oxide (MnO),manganese(III) oxide (Mn₂O₃).

894. The supercapacitor of any one of embodiments 884 to 893, wherein noion transport occurs from one electrode to the other as part of anelectrochemical reaction during charge or discharge.

895. The supercapacitor of any one of embodiments 884 to 894, wherein atleast one of the electrodes is configured substantially as one or bothof an electric double layer capacitor and a pseudo capacitor.

896. The supercapacitor of any one of embodiments 884 to 895, wherein atleast one of the electrodes is configured substantially as one of anelectric double layer capacitor or a pseudo capacitor while not beingconfigured substantially as the other of the double layer capacitor orthe pseudo capacitor.

897. The supercapacitor of any one of embodiments 884 to 896, whereinupon application of a voltage across the electrodes, a first sheet ofcharge of first polarity forms at surfaces of the surface activematerial of the at least one of the electrodes configured as an electricdouble layer capacitor, and a second sheet of charge of second polarityforms adjacent to the at least one of the electrodes configured as thedouble layer capacitor, wherein the first and second sheets of chargeare interposed by a layer of electrolyte.

898. The supercapacitor of any one of embodiments 884 to 897, whereinupon application of a voltage across the electrodes, the at least one ofthe electrodes configured as a pseudo capacitor stores energy by areversible Faradaic redox reaction on the surface of the surface activematerial.

899. The supercapacitor of any one of embodiments 884 to 899, whereinthe at least one of the electrodes comprising the zinc oxide areconfigured substantially as a pseudo capacitor.

900. The supercapacitor of any one of embodiments 890 to 892, whereinthe at least one of the electrodes comprising the CNTs are configuredsubstantially as an electric double layer capacitor.

901. The supercapacitor of any one of embodiments 884 to 900, whereinthe electrolyte comprises an ionic liquid.

902. The supercapacitor of any one of embodiments 884 to 901, whereinthe ionic liquid comprises one or more cations selected from the groupconsisting of butyltrimethylammonium, 1-ethyl-3-methylimidazolium,1-butyl-3-methylimidazolium, 1-methyl-3-propylimidazolium,1-hexyl-3-methylimidazolium, choline, ethylammonium,tributylmethylphosphonium, tributyl(tetradecyl)phosphonium,trihexyl(tetradecyl)phosphonium, 1-ethyl-2,3-methylimidazolium,1-butyl-1-methylpiperidinium, diethylmethylsulfonium,1-methyl-3-propylimidazolium, 1-ethyl-3-methylimidazolium,1-methyl-1-propylpiperidinium, 1-butyl-2-methylpyridinium,1-butyl-4-methylpyridinium, 1-butyl-1-methylpyrrolidinium,diethylmethylsulfonium and combinations thereof.

903. The supercapacitor of any one of embodiments 884 to 902, whereinthe ionic liquid comprises or more anions selected from the groupconsisting of tris(pentafluoroethyl)trifluorophosphate,trifluoromethanesulfonate, hexafluorophosphate, tetrafluoroborate, ethylsulfate, dimethyl phosphate, methansulfonate, triflate,tricyanomethanide, dibutylphosphate, bis(trifluoromethylsulfonyl)imide,bis-2,4,4-(trimethylpentyl) phosphinate, iodide, chloride, bromide,nitrate and combinations thereof.

904. The supercapacitor of any one of embodiments 884 to 903, whereinthe ionic liquid comprises 1-ethyl-3-methylimidazolium tetrafluoroborate(C₂mimBF₄).

905. The supercapacitor of any one of embodiments 884 to 904, whereinthe electrolyte further comprises a salt dissolved therein.

906. The supercapacitor of embodiment 905, wherein the salt has at leasta cation that is different from a cation of the ionic liquid.

907. The supercapacitor of embodiments 905 or 906, wherein the saltcomprises a cation selected from a group consisting of zinc, sodium,potassium, magnesium, calcium, aluminum, lithium, barium andcombinations thereof.

908. The supercapacitor of any one of embodiments 905 to 907, whereinthe salt comprises at least an anion that is different from an anion ofthe ionic liquid.

909. The supercapacitor of any one of embodiments 905 to 908, whereinthe salt comprises an anion selected from the group consisting ofchloride, bromide, fluoride, bis(trifluoromethanesulfonyl)imide,sulfate, bisulfite, nitrate, nitrite, carbonate, hydroxide, perchloride,bicarbonate, tetrafluoroborate, methansulfonate, acetate, phosphate,citrate, hexafluorophosphate and combinations thereof.

910. The supercapacitor of any one of embodiments 905 to 909, whereinthe salt comprises an organic salt.

911. The super capacitor of any one of embodiments 905 to 910, whereinthe salt comprises an anion selected from the group consisting oftetraethylammonium tetrafluoroborate, tetraethylammoniumdifluoro(oxalate)borate, methylammonium tetrafluoroborate,triethylmethylammonium tetrafluoroborate, tetrafluoroboric aciddimethyldi ethylammonium, triethylmethylammonium tetrafluoroborate,tetrapropylammonium tetrafluoroborate, methyltributylammoniumtetrafluoroborate, tetrabutylammonium tetrafluoroborate,tetrahexylammonium tetrafluoroborate, tetramethylammoniumtetrafluoroborate, tetraethyl phosphonium tetrafluoroborate,tetrapropylphosphonium tetrafluoroborate, tetrabutylphosphonium,tetrafluoroborate and combinations thereof.

912. The supercapacitor of any one of embodiments 905 to 909, whereinthe salt comprises an inorganic salt.

913. The supercapacitor of embodiment 912, wherein the inorganic saltcomprises a salt selected from the group consisting of LiCl; Li₂SO₄,LiClO₄, NaCl, Na₂SO₄, NaNO₃, KCl, K₂SO₄, KNO₃, Ca(NO₃)₂, MgSO₄ andcombinations thereof.

914. The supercapacitor of any one of embodiments 884 to 913, whereinthe electrolyte comprises an acid selected from the group consisting ofH₂SO₄, HCl, HNO₃, HClO₄ and combinations thereof.

915. The supercapacitor of any one of embodiments 884 to 913, whereinthe electrolyte comprises a base selected from the group consisting ofKOH, NaOH, LiOH, NH₄OH and combinations thereof.

916. The supercapacitor of any one of embodiments 905 to 907 and 909 to915, wherein the salt comprises the same anion as an anion of the ionicliquid.

917. The supercapacitor of embodiment 905, wherein the salt compriseszinc tetrafluoroborate Zn(BF₄)₂.

918. The supercapacitor of any one of embodiments 905 to 917, furthercomprising a separator interposed between the pair of electrodes.

919. The supercapacitor of embodiment 918, wherein the separatorcomprises a plurality of frustules.

920. The supercapacitor of embodiment 919, wherein the separator furthercomprises graphene oxide.

921. The supercapacitor of any one of embodiments 905 to 921, whereinthe frustules comprise chemically unmodified frustules.

922. A supercapacitor comprising a pair of electrodes contacting anelectrolyte, wherein at least one of the electrodes comprise a pluralityof frustules and carbon nanotubes (CNTs).

923. The supercapacitor of embodiment 922, wherein a surface of each ofthe frustules has one or more of the CNTs formed thereon.

924. The supercapacitor of embodiments 922 or 923, wherein at least oneof the electrodes further comprise at least one of zinc oxide andmanganese oxide.

925. The supercapacitor of any one of embodiments 922 to 924, whereinthe surface of each of the frustules has one or more of the at least oneof the zinc oxide and the manganese oxide formed thereon.

926. The supercapacitor of any one of embodiments 922 to 925, whereinthe surface of each of the frustules has formed thereon nanostructurescomprising the at least one of the zinc oxide and the manganese oxide.

927. The supercapacitor of any one of embodiments 924 to 926, whereinthe manganese oxide comprises one or more of manganese dioxide (MnO₂),manganese(II, III) oxide (Mn₃O₄), manganese(II) oxide (MnO),manganese(III) oxide (Mn₂O₃).

928. The supercapacitor of any one of embodiments 922 to 927, wherein noion transport occurs from one electrode to the other as part of anelectrochemical reaction during charge or discharge.

929. The supercapacitor of any one of embodiments 922 to 928, wherein atleast one of the electrodes is configured substantially as one or bothof an electric double layer capacitor and a pseudo capacitor.

930. The supercapacitor of any one of embodiments 922 to 929, wherein atleast one of the electrodes is configured substantially as one of anelectric double layer capacitor or a pseudo capacitor while not beingconfigured substantially as the other of the double layer capacitor orthe pseudo capacitor.

931. The supercapacitor of any one of embodiments 922 to 930, whereinupon application of a voltage across the electrodes, a first sheet ofcharge of first polarity forms at surfaces of the surface activematerial of the at least one of the electrodes configured as an electricdouble layer capacitor, and a second sheet of charge of second polarityforms adjacent to the at least one of the electrodes configured as thedouble layer capacitor, wherein the first and second sheets of chargeare interposed by a layer of electrolyte.

932. The supercapacitor of any one of embodiments 922 to 931, whereinupon application of a voltage across the electrodes, the at least one ofthe electrodes configured as a pseudo capacitor stores energy by areversible Faradaic redox reaction on the surface of the surface activematerial.

933. The supercapacitor of any one of embodiments 922 to 932, whereinthe at least one of the electrodes comprising the at least one of thezinc oxide and the manganese oxide are configured substantially as apseudo capacitor.

934. The supercapacitor of any one of embodiments 922 to 932, whereinthe at least one of the electrodes are configured substantially as anelectric double layer capacitor.

935. The supercapacitor of any one of embodiments 922 to 934, whereinthe electrolyte comprises an ionic liquid.

936. The supercapacitor of any one of embodiments 922 to 935, whereinthe ionic liquid comprises one or more cations selected from the groupconsisting of butyltrimethylammonium, 1-ethyl-3-methylimidazolium,1-butyl-3-methylimidazolium, 1-methyl-3-propylimidazolium,1-hexyl-3-methylimidazolium, choline, ethylammonium,tributylmethylphosphonium, tributyl(tetradecyl)phosphonium,trihexyl(tetradecyl)phosphonium, 1-ethyl-2,3-methylimidazolium,1-butyl-1-methylpiperidinium, diethylmethylsulfonium,1-methyl-3-propylimidazolium, 1-ethyl-3-methylimidazolium,1-methyl-1-propylpiperidinium, 1-butyl-2-methylpyridinium,1-butyl-4-methylpyridinium, 1-butyl-1-methylpyrrolidinium,diethylmethylsulfonium and combinations thereof.

937. The supercapacitor of any one of embodiments 922 to 936, whereinthe ionic liquid comprises or more anions selected from the groupconsisting of tris(pentafluoroethyl)trifluorophosphate,trifluoromethanesulfonate, hexafluorophosphate, tetrafluoroborate, ethylsulfate, dimethyl phosphate, methansulfonate, triflate,tricyanomethanide, dibutylphosphate, bis(trifluoromethylsulfonyl)imide,bis-2,4,4-(trimethylpentyl) phosphinate, iodide, chloride, bromide,nitrate and combinations thereof.

938. The supercapacitor of embodiment 935, wherein the ionic liquidcomprises 1-ethyl-3-methylimidazolium tetrafluoroborate (C₂mimB F4).

939. The supercapacitor of any one of embodiments 922 to 938, whereinthe electrolyte further comprises a salt dissolved therein.

940. The supercapacitor of embodiment 939, wherein the salt has at leasta cation that is different from a cation of the ionic liquid.

941. The supercapacitor of embodiments 939 or 940, wherein the saltcomprises a cation selected from a group consisting of zinc, sodium,potassium, magnesium, calcium, aluminum, lithium, barium andcombinations thereof.

942. The supercapacitor of any one of embodiments 939 to 941, whereinthe salt comprises at least an anion that is different from an anion ofthe ionic liquid.

943. The supercapacitor of any one of embodiments 939 to 942, whereinthe salt comprises an anion selected from the group consisting ofchloride, bromide, fluoride, bis(trifluoromethanesulfonyl)imide,sulfate, bisulfite, nitrate, nitrite, carbonate, hydroxide, perchloride,bicarbonate, tetrafluoroborate, methansulfonate, acetate, phosphate,citrate, hexafluorophosphate and combinations thereof.

944. The supercapacitor of any one of embodiments 939 to 943, whereinthe salt comprises an organic salt.

945. The supercapacitor of any one of embodiments 939 to 944, whereinthe salt comprises an anion selected from the group consisting oftetraethylammonium tetrafluoroborate, tetraethylammoniumdifluoro(oxalate)borate, methylammonium tetrafluoroborate,triethylmethylammonium tetrafluoroborate, tetrafluoroboric aciddimethyldi ethylammonium, triethylmethylammonium tetrafluoroborate,tetrapropylammonium tetrafluoroborate, methyltributylammoniumtetrafluoroborate, tetrabutylammonium tetrafluoroborate,tetrahexylammonium tetrafluoroborate, tetramethylammoniumtetrafluoroborate, tetraethyl phosphonium tetrafluoroborate,tetrapropylphosphonium tetrafluoroborate, tetrabutylphosphonium,tetrafluoroborate and combinations thereof.

946. The supercapacitor of any one of embodiments 939 to 943, whereinthe salt comprises an inorganic salt.

947. The supercapacitor of embodiment 946, wherein the inorganic saltcomprises a salt selected from the group consisting of LiCl; Li₂SO₄,LiClO₄, NaCl, Na₂SO₄, NaNO₃, KCl, K₂SO₄, KNO₃, Ca(NO₃)₂, MgSO₄ andcombinations thereof.

948. The supercapacitor of any one of embodiments 922 to 947, whereinthe electrolyte comprises an acid selected from the group consisting ofH₂SO₄, HCl, HNO₃, HClO₄ and combinations thereof.

949. The supercapacitor of any one of embodiments 922 to 947, whereinthe electrolyte comprises a base selected from the group consisting ofKOH, NaOH, LiOH, NH₄OH and combinations thereof.

950. The supercapacitor of any one of embodiments 939 to 941 and 943 to949, wherein the salt comprises the same anion as an anion of the ionicliquid.

951. The supercapacitor of embodiment 950, wherein the salt compriseszinc tetrafluoroborate Zn(BF₄)₂.

952. The supercapacitor of any one of embodiments 922 to 951, furthercomprising a separator interposed between the pair of electrodes.

953. The supercapacitor of embodiment 952, wherein the separatorcomprises a plurality of frustules.

954. The supercapacitor of embodiment 953, wherein the separator furthercomprises graphene oxide.

955. The supercapacitor of any one of embodiments 922 to 954, whereinthe frustules comprise chemically unmodified frustules.

956. A method of fabricating a supercapacitor, the method comprising:forming a separator between a pair of electrodes, wherein the separatorcomprises frustules, an electrolyte and a thermally conductive additive,wherein the thermally conductive additive is adapted to substantiallyabsorb a near infrared (NIR) radiation upon being applied to theseparator, thereby causing heating of the separator to acceleratedrying.

957. The method of embodiment 956, wherein the thermally conductiveadditive is substantially thermally conducting and substantiallyelectrically insulating.

958. The method of embodiments 956 or 957, wherein the thermallyconductive additive comprises graphene oxide (GO).

959. The method of embodiment 958, wherein the GO comprises a network ofcontiguous sheets contacting each other.

960. The method of any one of embodiments 956 to 959, wherein theforming the separator comprises forming a mixture comprising thefrustules, a gel and the electrolyte.

961. The method of embodiment 960, wherein the electrolyte comprises oneor more of a solvent, a salt and an ionic liquid.

962. The method of embodiments 960 or 961, wherein the gel comprises agelling polymer.

963. The method of embodiment 962, wherein the gelling polymer includesone or more selected from the group consisting of polyvinylidenefluoride, polyacrylic acid, polyethylene oxide, polyvinyl alcohol andcombinations thereof.

964. The method of embodiments 962 or 963, wherein the gel comprises thegelling polymer and the electrolyte.

965. The method of any one of embodiments 960 to 964, wherein thefrustules form a network of pores, wherein forming the mixture comprisessubstantially completely filling the network of pores with the gel.

966. The method of any one of embodiments 960 to 964, wherein thefrustules form a network of pores, wherein forming the mixture comprisespartly filling the network of pores with the gel.

967. The method of embodiment 964, wherein forming the mixture comprisesfiling the network unfilled with the gel with the electrolyte.

968. The method of any one of embodiments 956-967, wherein forming theseparator comprises printing using an ink comprising the frustules andthe thermally conductive additive.

969. The method of any one of embodiments 956 to 968, wherein theseparator comprises an electrolyte comprising an ionic liquid.

970. The method of embodiment 969, wherein the ionic liquid comprisesone or more cations selected from the group consisting ofbutyltrimethylammonium, 1-ethyl-3-methylimidazolium,1-butyl-3-methylimidazolium, 1-methyl-3-propylimidazolium,1-hexyl-3-methylimidazolium, choline, ethylammonium, tributylmethylphosphonium, tributyl(tetradecyl)pho sphonium, trihexyl(tetradecyl)phosphonium, 1-ethyl-2,3-methylimidazolium, 1-butyl-1-methylpiperidinium,diethylmethylsulfonium, 1-methyl-3-propylimidazolium,1-ethyl-3-methylimidazolium, 1-methyl-1-propylpiperidinium,1-butyl-2-methylpyridinium, 1-butyl-4-methylpyridinium,1-butyl-1-methylpyrrolidinium, diethylmethylsulfonium and combinationsthereof.

971. The method of embodiments 969 or 970, wherein the ionic liquidcomprises or more anions selected from the group consisting oftris(pentafluoroethyl)trifluoropho sphate, trifluoromethanesulfonate,hexafluoropho sphate, tetrafluoroborate, ethyl sulfate, dimethylphosphate, methansulfonate, triflate, tricyanomethanide, dibutylphosphate, bis(trifluoromethylsulfonyl)imide, bis-2,4,4-(trimethylpentyl)phosphinate, iodide, chloride, bromide, nitrate and combinationsthereof.

972. The method of any one of embodiments 969 to 971, wherein the ionicliquid comprises 1-ethyl-3-methylimidazolium tetrafluoroborate(C₂mimBF₄).

973. The method of any one of embodiments 969 to 972, wherein theelectrolyte further comprises a salt dissolved therein.

974. The method of embodiment 973, wherein the salt comprises a cationselected from a group consisting of zinc, sodium, potassium, magnesium,calcium, aluminum, lithium, barium and combinations thereof.

975. The method of embodiments 973 or 974, wherein the salt comprises atleast an anion that is different from an anion of the ionic liquid.

976. The method of any one of embodiments 973 to 975, wherein the saltcomprises an anion selected from the group consisting of chloride,bromide, fluoride, bis(trifluoromethanesulfonyl)imide, sulfate,bisulfite, nitrate, nitrite, carbonate, hydroxide, perchloride,bicarbonate, tetrafluoroborate, methansulfonate, acetate, phosphate,citrate, hexafluorophosphate and combinations thereof.

977. The method of any one of embodiments 973 to 976, wherein the saltcomprises an organic salt.

978. The method of any one of embodiments 973 to 977, wherein the saltcomprises an anion selected from the group consisting oftetraethylammonium tetrafluoroborate, tetraethylammoniumdifluoro(oxalate)borate, methylammonium tetrafluoroborate,triethylmethylammonium tetrafluoroborate, tetrafluoroboric aciddimethyldi ethylammonium, triethylmethylammonium tetrafluoroborate,tetrapropylammonium tetrafluoroborate, methyltributylammoniumtetrafluoroborate, tetrabutylammonium tetrafluoroborate,tetrahexylammonium tetrafluoroborate, tetramethylammoniumtetrafluoroborate, tetraethyl phosphonium tetrafluoroborate,tetrapropylphosphonium tetrafluoroborate, tetrabutylphosphonium,tetrafluoroborate and combinations thereof.

979. The method of any one of embodiments 973 to 978, wherein the saltcomprises an inorganic salt.

980. The method of embodiment 979, wherein the inorganic salt comprisesa salt selected from the group consisting of LiC1, Li₂SO₄, LiClO₄, NaCl,Na₂SO₄, NaNO₃, KCl, K₂SO₄, KNO₃, Ca(NO₃)₂, MgSO₄ and combinationsthereof.

981. The method of any one of embodiments 969 to 980, wherein theelectrolyte comprises an acid selected from the group consisting ofH₂SO₄, HCl, HNO₃, HClO₄ and combinations thereof.

982. The method of any one of embodiments 969 to 980, wherein theelectrolyte comprises a base selected from the group consisting of KOH,NaOH, LiOH, NH₄OH and combinations thereof.

983. The method of any one of embodiments 973 to 980, wherein the saltcomprises the same anion as an anion of the ionic liquid.

984. The method of any one of embodiments 973 to 980, wherein the saltcomprises zinc tetrafluoroborate Zn(BF₄)₂.

985. The method of any one of embodiments 956 to 984, further comprisingdrying the separator by subjecting the separator to the NIR radiation.

986. The method of embodiment 985, wherein drying the separator isperformed for a duration not exceeding 1 minute.The method of any one ofembodiments 956 to 985, wherein the supercapacitor is according to anyone of embodiments 803 to 847.

987. The method of any one of embodiments 956 to 985, wherein thesupercacitor is according to any one of embodiments 848 to 883.

988. The method of any one of embodiments 956 to 985, wherein thesupercacitor is according to any one of embodiments 884 to 955.

989. The method of any one of embodiments 956 to 985, wherein one ormore components of the supercapacitor are manufactured according to themethod of manufacturing the printed energy storage device according toany one of embodiments 98 to 115.

990. The method of any one of embodiments 956 to 985, wherein one ormore components of the supercapacitor are printed using the inkaccording to any one of embodiments 116 to 154.

991. The method of any one of embodiments 956 to 985, wherein thefrustules are extracted according to any one of embodiments 160 to 321.

992. The method of any one of embodiments 956 to 985, wherein one ormore components of the supercapacitor are printed using the inkaccording to any one of embodiments 520 to 524.

993. The method of any one of embodiments 956 to 985, wherein at leastsome of the frustules comprise a surface active material comprisingmanganese-containing nanostructures formed according to any one ofembodiments 525 to 546.

994. The method of any one of embodiments 956 to 985, wherein at leastsome of the frustules comprise a surface active material comprisingzinc-oxide nanostructures formed according to any one of embodiments 620to 644.

995. The method of any one of embodiments 956 to 985, wherein at leastsome of the frustules comprise a surface active material comprising theoxide of manganese formed according to any one of embodiments 645 to655.

996. The method of any one of embodiments 956 to 985, wherein one ormore components of the supercapacitor are printed using the inkaccording to any one of embodiments 656 to 683.

997. The method of any one of embodiments 956 to 985, wherein one ormore components of the supercapacitor are printed using the ink preparedaccording to any one of embodiments 684 to 705.

998. The method of any one of embodiments 956 to 985, wherein one ormore components of the supercapacitor are formed according to any one ofembodiments 706 to 739.

While the methods and devices described herein may be susceptible tovarious modifications and alternative forms, specific examples thereofhave been shown in the drawings and are herein described in detail. Itshould be understood, however, that the invention is not to be limitedto the particular forms or methods disclosed, but, to the contrary, theinvention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the various implementationsdescribed and the appended claims. It is also contemplated that variouscombinations or sub-combinations of the specific features and aspects ofthe embodiments may be made and still fall within the scope of theinvention. It should be understood that various features and aspects ofthe disclosed embodiments can be combined with, or substituted for, oneanother in order to form varying modes of the embodiments of thedisclosed invention. Further, the disclosure herein of any particularfeature, aspect, method, property, characteristic, quality, attribute,element, or the like in connection with an implementation or embodimentcan be used in all other implementations or embodiments set forthherein.

Any methods disclosed herein need not be performed in the order recited.The methods disclosed herein may include certain actions taken by apractitioner; however, the methods can also include any third-partyinstruction of those actions, either expressly or by implication. Forexample, actions such as “adding the frustules to an oxygenatedmanganese acetate solution” include “instructing the adding of thefrustules to an oxygenated manganese acetate solution.”

The ranges disclosed herein also encompass any and all overlap,sub-ranges, and combinations thereof. Language such as “up to,” “atleast,” “greater than,” “less than,” “between,” and the like includesthe number recited. Numbers preceded by a term such as “about” or“approximately” include the recited numbers and should be interpretedbased on the circumstances (e.g., as accurate as reasonably possibleunder the circumstances, for example ±5%, ±10%, ±15%, etc.). Forexample, “about 3.5 mm” includes “3.5 mm.” Phrases preceded by a termsuch as “substantially” include the recited phrase and should beinterpreted based on the circumstances (e.g., as much as reasonablypossible under the circumstances). For example, “substantially constant”includes “constant.”

The headings provided herein, if any, are for convenience only and donot necessarily affect the scope or meaning of the devices and methodsdisclosed herein.

What is claimed is:
 1. A supercapacitor configured to charge anddischarge through an electrochemical process, the supercapacitorcomprising: a pair of electrodes contacting an electrolyte, wherein oneof the electrodes comprises frustules coated with a plurality of carbonnanotubes, and wherein the other of the electrodes comprises frustulescoated with an active material.
 2. The supercapacitor of claim 1,wherein the active material comprises a transition metal oxide.
 3. Thesupercapacitor of claim 2, wherein the transition metal oxide comprisesa zinc oxide.
 4. The supercapacitor of claim 2, wherein the transitionmetal oxide comprises a manganese oxide.
 5. The supercapacitor of claim4, wherein the manganese oxide comprises one or more of manganesedioxide (MnO₂), manganese (II, III) oxide (Mn₃O₄), manganese(II) oxide(MnO), or manganese (III) oxide (Mn₂O₃).
 6. The supercapacitor of claim1, wherein no ion transport occurs as part of an electrochemicalreaction between the one of the electrodes and the other of theelectrodes during charge or discharge.
 7. The supercapacitor of claim 1,wherein the electrolyte comprises an ionic liquid.
 8. The supercapacitorof claim 7, wherein the ionic liquid comprises one or more cationsselected from the group consisting of butyltrimethylammonium,1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium,1-methyl-3-propylimidazolium, 1-hexyl-3-methylimidazolium, choline,ethylammonium, tributylmethylphosphonium,tributyl(tetradecyl)phosphonium, trihexyl(tetradecyl)phosphonium,1-ethyl-2,3-methylimidazolium, 1-butyl-1-methylpiperidinium,1-ethyl-3-methylimidazolium, 1-methyl-1-propylpiperidinium,1-butyl-2-methylpyridinium, 1-butyl-4-methylpyridinium,1-butyl-1-methylpyrrolidinium, diethylmethylsulfonium or a combinationthereof.
 9. The supercapacitor of claim 7, wherein the ionic liquidcomprises one or more anions selected from the group consisting oftris(pentafluoroethyl)trifluorophosphate, trifluoromethanesulfonate,hexafluorophosphate, tetrafluoroborate, ethyl sulfate, dimethylphosphate, methanesulfonate, triflate, tricyanomethanide,dibutylphosphate, bis(trifluoromethylsulfonyl)imide,bis-2,4,4-(trimethylpentyl) phosphinate, iodide, chloride, bromide,nitrate or a combination thereof.
 10. A supercapacitor configured tocharge and discharge through an electrochemical process, thesupercapacitor comprising: a pair of electrodes contacting anelectrolyte, wherein each of the electrodes comprises a plurality offrustules, and wherein one but not the other of the electrodes furthercomprises carbon nanotubes coating the frustules.
 11. The supercapacitorof claim 10, wherein at least some of the frustules of the one of theelectrodes are individually coated with the plurality of carbonnanotubes.
 12. The supercapacitor of claim 10, wherein the frustules ofthe other of the electrodes or both of the electrodes have formedthereon one or more transition metal oxides.
 13. The supercapacitor ofclaim 12, wherein the one or more transition metal oxides comprise azinc oxide.
 14. The supercapacitor of claim 12, wherein the one or moretransition metal oxides comprise a manganese oxide.
 15. Thesupercapacitor of claim 14, wherein the manganese oxide comprises one ormore of manganese dioxide (MnO₂), manganese (II, III) oxide (Mn₃O₄),manganese(II) oxide (MnO), or manganese (III) oxide (Mn₂O₃).
 16. Thesupercapacitor of claim 10, wherein no ion transport occurs as part ofan electrochemical reaction between the one of the electrodes and theother of the electrodes during charge or discharge.
 17. Thesupercapacitor of claim 10, wherein the electrolyte comprises an ionicliquid.
 18. A supercapacitor configured to charge and discharge throughan electrochemical process, the supercapacitor comprising: a pair ofelectrodes contacting an electrolyte, wherein one of the electrodescomprises a plurality of frustules and a plurality of carbon nanotubes,and wherein the one of the electrodes is configured substantially as anelectric double layer capacitor, while the other of the electrodes isconfigured substantially as a pseudo capacitor.
 19. The supercapacitorof claim 18, wherein the one of the electrodes comprises individual onesof the frustules coated with the carbon nanotubes.
 20. Thesupercapacitor of claim 18, wherein the other of the electrodescomprises individual ones of the frustules coated with a transitionmetal oxide.